Added: tinkerpop/site/docs/3.2.6-SNAPSHOT/tutorials/gremlin-language-variants/index.html URL: http://svn.apache.org/viewvc/tinkerpop/site/docs/3.2.6-SNAPSHOT/tutorials/gremlin-language-variants/index.html?rev=1799018&view=auto ============================================================================== --- tinkerpop/site/docs/3.2.6-SNAPSHOT/tutorials/gremlin-language-variants/index.html (added) +++ tinkerpop/site/docs/3.2.6-SNAPSHOT/tutorials/gremlin-language-variants/index.html Sat Jun 17 18:56:29 2017 @@ -0,0 +1,1541 @@ +<!DOCTYPE html> +<html lang="en"> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> +<meta name="generator" content="Asciidoctor 0.1.4"> +<meta name="viewport" content="width=device-width, initial-scale=1.0"> +<title>Gremlin Language Variants</title> +<style> +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + */ + +/*! normalize.css v2.1.2 | MIT License | git.io/normalize */ +/* ========================================================================== HTML5 display definitions ========================================================================== */ +/** Correct `block` display not defined in IE 8/9. */ +@import url(http://cdnjs.cloudflare.com/ajax/libs/font-awesome/3.2.1/css/font-awesome.css); +article, aside, details, figcaption, figure, footer, header, hgroup, main, nav, section, summary { display: block; } + +/** Correct `inline-block` display not defined in IE 8/9. */ +audio, canvas, video { display: inline-block; } + +/** Prevent modern browsers from displaying `audio` without controls. Remove excess height in iOS 5 devices. */ +audio:not([controls]) { display: none; height: 0; } + +/** Address `[hidden]` styling not present in IE 8/9. 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} +ul.no-bullet, ol.no-bullet { margin-left: 0; } + +/* Unordered Lists */ +ul li ul, ul li ol { margin-left: 1.25em; margin-bottom: 0; font-size: 1em; /* Override nested font-size change */ } +ul.square li ul, ul.circle li ul, ul.disc li ul { list-style: inherit; } +ul.square { list-style-type: square; } +ul.circle { list-style-type: circle; } +ul.disc { list-style-type: disc; } +ul.no-bullet { list-style: none; } + +/* Ordered Lists */ +ol li ul, ol li ol { margin-left: 1.25em; margin-bottom: 0; } + +/* Definition Lists */ +dl dt { margin-bottom: 0.3em; font-weight: bold; } +dl dd { margin-bottom: 0.75em; } + +/* Abbreviations */ +abbr, acronym { text-transform: uppercase; font-size: 90%; color: black; border-bottom: 1px dotted #dddddd; cursor: help; } + +abbr { text-transform: none; } + +/* Blockquotes */ +blockquote { margin: 0 0 1.25em; padding: 0.5625em 1.25em 0 1.1875em; border-left: 1px solid #dddddd; } +blockquote cite { display: block; font-size: 0.8125em; color: #748590; } +blockquote cite:before { content: "\2014 \0020"; } +blockquote cite a, blockquote cite a:visited { color: #748590; } + +blockquote, blockquote p { line-height: 1.5; color: #909ea7; } + +/* Microformats */ +.vcard { display: inline-block; margin: 0 0 1.25em 0; border: 1px solid #dddddd; padding: 0.625em 0.75em; } +.vcard li { margin: 0; display: block; } +.vcard .fn { font-weight: bold; font-size: 0.9375em; } + +.vevent .summary { font-weight: bold; } +.vevent abbr { cursor: auto; text-decoration: none; font-weight: bold; border: none; padding: 0 0.0625em; } + +@media only screen and (min-width: 768px) { h1, h2, h3, #toctitle, .sidebarblock > .content > .title, h4, h5, h6 { line-height: 1.4; } + h1 { font-size: 2.75em; } + h2 { font-size: 2.3125em; } + h3, #toctitle, .sidebarblock > .content > .title { font-size: 1.6875em; } + h4 { font-size: 1.4375em; } } +/* Print styles. Inlined to avoid required HTTP connection: www.phpied.com/delay-loading-your-print-css/ Credit to Paul Irish and HTML5 Boilerplate (html5boilerplate.com) +*/ +.print-only { display: none !important; } + +@media print { * { background: transparent !important; color: #000 !important; /* Black prints faster: h5bp.com/s */ box-shadow: none !important; text-shadow: none !important; } + a, a:visited { text-decoration: underline; } + a[href]:after { content: " (" attr(href) ")"; } + abbr[title]:after { content: " (" attr(title) ")"; } + .ir a:after, a[href^="javascript:"]:after, a[href^="#"]:after { content: ""; } + pre, blockquote { border: 1px solid #999; page-break-inside: avoid; } + thead { display: table-header-group; /* h5bp.com/t */ } + tr, img { page-break-inside: avoid; } + img { max-width: 100% !important; } + @page { margin: 0.5cm; } + p, h2, h3, #toctitle, .sidebarblock > .content > .title { orphans: 3; widows: 3; } + h2, h3, #toctitle, .sidebarblock > .content > .title { page-break-after: avoid; } + .hide-on-print { display: none !important; } + .print-only { display: block !important; } + .hide-for-print { display: none !important; } + .show-for-print { display: inherit !important; } } +/* Tables */ +table { background: white; margin-bottom: 1.25em; border: solid 0 #dddddd; } +table thead, table tfoot { background: none; font-weight: bold; } +table thead tr th, table thead tr td, table tfoot tr th, table tfoot tr td { padding: 1px 8px 1px 5px; font-size: 1em; color: #222222; text-align: left; } +table tr th, table tr td { padding: 1px 8px 1px 5px; font-size: 1em; color: #222222; } +table tr.even, table tr.alt, table tr:nth-of-type(even) { background: none; } +table thead tr th, table tfoot tr th, table tbody tr td, table tr td, table tfoot tr td { display: table-cell; line-height: 1.5; } + +.clearfix:before, .clearfix:after, .float-group:before, .float-group:after { content: " "; display: table; } +.clearfix:after, .float-group:after { clear: both; } + +*:not(pre) > code { font-size: 0.95em; padding: 0; white-space: nowrap; background-color: #f2f2f2; border: 0 solid #dddddd; -webkit-border-radius: 6px; border-radius: 6px; text-shadow: none; } + +pre, pre > code { line-height: 1.2; color: inherit; font-family: "Consolas", "Deja Vu Sans Mono", "Bitstream Vera Sans Mono", monospace; font-weight: normal; } + +.keyseq { color: #333333; } + +kbd:not(.keyseq) { display: inline-block; color: black; font-size: 0.75em; line-height: 1.4; background-color: #F7F7F7; border: 1px solid #ccc; -webkit-border-radius: 3px; border-radius: 3px; -webkit-box-shadow: 0 1px 0 rgba(0, 0, 0, 0.2), 0 0 0 2px white inset; box-shadow: 0 1px 0 rgba(0, 0, 0, 0.2), 0 0 0 2px white inset; margin: -0.15em 0.15em 0 0.15em; padding: 0.2em 0.6em 0.2em 0.5em; vertical-align: middle; white-space: nowrap; } + +.keyseq kbd:first-child { margin-left: 0; } + +.keyseq kbd:last-child { margin-right: 0; } + +.menuseq, .menu { color: black; } + +b.button:before, b.button:after { position: relative; top: -1px; font-weight: normal; } + +b.button:before { content: "["; padding: 0 3px 0 2px; } + +b.button:after { content: "]"; padding: 0 2px 0 3px; } + +p a > code:hover { color: #373737; } + +#header, #content, #footnotes, #footer { width: 100%; margin-left: auto; margin-right: auto; margin-top: 0; margin-bottom: 0; max-width: 62.5em; *zoom: 1; position: relative; padding-left: 0.9375em; padding-right: 0.9375em; } +#header:before, #header:after, #content:before, #content:after, #footnotes:before, #footnotes:after, #footer:before, #footer:after { content: " "; display: table; } +#header:after, #content:after, #footnotes:after, #footer:after { clear: both; } + +#header { margin-bottom: 2.5em; } +#header > h1 { color: #111111; font-weight: bold; border-bottom: 1px solid #dddddd; margin-bottom: -28px; padding-bottom: 32px; } +#header span { color: #909ea7; } +#header #revnumber { text-transform: capitalize; } +#header br { display: none; } +#header br + span { padding-left: 3px; } +#header br + span:before { content: "\2013 \0020"; } +#header br + span.author { padding-left: 0; } +#header br + span.author:before { content: ", "; } + +#toc { border-bottom: 1px solid #dddddd; padding-bottom: 1.25em; } +#toc > ul { margin-left: 0.25em; } +#toc ul.sectlevel0 > li > a { font-style: italic; } +#toc ul.sectlevel0 ul.sectlevel1 { margin-left: 0; margin-top: 0.5em; margin-bottom: 0.5em; } +#toc ul { list-style-type: none; } + +#toctitle { color: #6c818f; } + +@media only screen and (min-width: 768px) { body.toc2 { padding-left: 15em; padding-right: 0; } + #toc.toc2 { position: fixed; width: 15em; left: 0; top: 0; border-right: 1px solid #dddddd; border-bottom: 0; z-index: 1000; padding: 1em; height: 100%; overflow: auto; } + #toc.toc2 #toctitle { margin-top: 0; font-size: 1.2em; } + #toc.toc2 > ul { font-size: .90em; } + #toc.toc2 ul ul { margin-left: 0; padding-left: 1em; } + #toc.toc2 ul.sectlevel0 ul.sectlevel1 { padding-left: 0; margin-top: 0.5em; margin-bottom: 0.5em; } + body.toc2.toc-right { padding-left: 0; padding-right: 15em; } + body.toc2.toc-right #toc.toc2 { border-right: 0; border-left: 1px solid #dddddd; left: auto; right: 0; } } +@media only screen and (min-width: 1280px) { body.toc2 { padding-left: 20em; padding-right: 0; } + #toc.toc2 { width: 20em; } + #toc.toc2 #toctitle { font-size: 1.375em; } + #toc.toc2 > ul { font-size: 0.95em; } + #toc.toc2 ul ul { padding-left: 1.25em; } + body.toc2.toc-right { padding-left: 0; padding-right: 20em; } } +#content #toc { border-style: solid; border-width: 1px; border-color: #d9d9d9; margin-bottom: 1.25em; padding: 1.25em; background: #f2f2f2; border-width: 0; -webkit-border-radius: 6px; border-radius: 6px; } +#content #toc > :first-child { margin-top: 0; } +#content #toc > :last-child { margin-bottom: 0; } +#content #toc a { text-decoration: none; } + +#content #toctitle { font-weight: bold; font-family: ff-meta-web-pro-1, ff-meta-web-pro-2, Arial, "Helvetica Neue", sans-serif; font-size: 1em; padding-left: 0.125em; } + +#footer { max-width: 100%; background-color: black; padding: 1.25em; } + +#footer-text { color: white; line-height: 1.35; } + +.sect1 { padding-bottom: 1.25em; } + +.sect1 + .sect1 { border-top: 1px solid #dddddd; } + +#content h1 > a.anchor, h2 > a.anchor, h3 > a.anchor, #toctitle > a.anchor, .sidebarblock > .content > .title > a.anchor, h4 > a.anchor, h5 > a.anchor, h6 > a.anchor { position: absolute; width: 1em; margin-left: -1em; display: block; text-decoration: none; visibility: hidden; text-align: center; font-weight: normal; } +#content h1 > a.anchor:before, h2 > a.anchor:before, h3 > a.anchor:before, #toctitle > a.anchor:before, .sidebarblock > .content > .title > a.anchor:before, h4 > a.anchor:before, h5 > a.anchor:before, h6 > a.anchor:before { content: '\00A7'; font-size: .85em; vertical-align: text-top; display: block; margin-top: 0.05em; } +#content h1:hover > a.anchor, #content h1 > a.anchor:hover, h2:hover > a.anchor, h2 > a.anchor:hover, h3:hover > a.anchor, #toctitle:hover > a.anchor, .sidebarblock > .content > .title:hover > a.anchor, h3 > a.anchor:hover, #toctitle > a.anchor:hover, .sidebarblock > .content > .title > a.anchor:hover, h4:hover > a.anchor, h4 > a.anchor:hover, h5:hover > a.anchor, h5 > a.anchor:hover, h6:hover > a.anchor, h6 > a.anchor:hover { visibility: visible; } +#content h1 > a.link, h2 > a.link, h3 > a.link, #toctitle > a.link, .sidebarblock > .content > .title > a.link, h4 > a.link, h5 > a.link, h6 > a.link { color: #465158; text-decoration: none; } +#content h1 > a.link:hover, h2 > a.link:hover, h3 > a.link:hover, #toctitle > a.link:hover, .sidebarblock > .content > .title > a.link:hover, h4 > a.link:hover, h5 > a.link:hover, h6 > a.link:hover { color: #3b444a; } + +.imageblock, .literalblock, .listingblock, .mathblock, .verseblock, .videoblock { margin-bottom: 1.25em; } + +.admonitionblock td.content > .title, .exampleblock > .title, .imageblock > .title, .listingblock > .title, .literalblock > .title, .mathblock > .title, .openblock > .title, .paragraph > .title, .quoteblock > .title, .sidebarblock > .title, .tableblock > .title, .verseblock > .title, .videoblock > .title, .dlist > .title, .olist > .title, .ulist > .title, .qlist > .title, .hdlist > .title { text-align: left; font-weight: bold; } + +.tableblock > caption { text-align: left; font-weight: bold; white-space: nowrap; overflow: visible; max-width: 0; } + +table.tableblock #preamble > .sectionbody > .paragraph:first-of-type p { font-size: inherit; } + +.admonitionblock > table { border: 0; background: none; width: 100%; } +.admonitionblock > table td.icon { text-align: center; width: 80px; } +.admonitionblock > table td.icon img { max-width: none; } +.admonitionblock > table td.icon .title { font-weight: bold; text-transform: uppercase; } +.admonitionblock > table td.content { padding-left: 1.125em; padding-right: 1.25em; border-left: 1px solid #dddddd; color: #909ea7; } +.admonitionblock > table td.content > :last-child > :last-child { margin-bottom: 0; } + +.exampleblock > .content { border-style: solid; border-width: 1px; border-color: #e6e6e6; margin-bottom: 1.25em; padding: 1.25em; background: white; -webkit-border-radius: 6px; border-radius: 6px; } +.exampleblock > .content > :first-child { margin-top: 0; } +.exampleblock > .content > :last-child { margin-bottom: 0; } +.exampleblock > .content h1, .exampleblock > .content h2, .exampleblock > .content h3, .exampleblock > .content #toctitle, .sidebarblock.exampleblock > .content > .title, .exampleblock > .content h4, .exampleblock > .content h5, .exampleblock > .content h6, .exampleblock > .content p { color: #333333; } +.exampleblock > .content h1, .exampleblock > .content h2, .exampleblock > .content h3, .exampleblock > .content #toctitle, .sidebarblock.exampleblock > .content > .title, .exampleblock > .content h4, .exampleblock > .content h5, .exampleblock > .content h6 { line-height: 1; margin-bottom: 0.625em; } +.exampleblock > .content h1.subheader, .exampleblock > .content h2.subheader, .exampleblock > .content h3.subheader, .exampleblock > .content .subheader#toctitle, .sidebarblock.exampleblock > .content > .subheader.title, .exampleblock > .content h4.subheader, .exampleblock > .content h5.subheader, .exampleblock > .content h6.subheader { line-height: 1.4; } + +.exampleblock.result > .content { -webkit-box-shadow: 0 1px 8px #d9d9d9; box-shadow: 0 1px 8px #d9d9d9; } + +.sidebarblock { border-style: solid; border-width: 1px; border-color: #d9d9d9; margin-bottom: 1.25em; padding: 1.25em; background: #f2f2f2; -webkit-border-radius: 6px; border-radius: 6px; } +.sidebarblock > :first-child { margin-top: 0; } +.sidebarblock > :last-child { margin-bottom: 0; } +.sidebarblock h1, .sidebarblock h2, .sidebarblock h3, .sidebarblock #toctitle, .sidebarblock > .content > .title, .sidebarblock h4, .sidebarblock h5, .sidebarblock h6, .sidebarblock p { color: #333333; } +.sidebarblock h1, .sidebarblock h2, .sidebarblock h3, .sidebarblock #toctitle, .sidebarblock > .content > .title, .sidebarblock h4, .sidebarblock h5, .sidebarblock h6 { line-height: 1; margin-bottom: 0.625em; } +.sidebarblock h1.subheader, .sidebarblock h2.subheader, .sidebarblock h3.subheader, .sidebarblock .subheader#toctitle, .sidebarblock > .content > .subheader.title, .sidebarblock h4.subheader, .sidebarblock h5.subheader, .sidebarblock h6.subheader { line-height: 1.4; } +.sidebarblock > .content > .title { color: #6c818f; margin-top: 0; line-height: 1.5; } + +.exampleblock > .content > :last-child > :last-child, .exampleblock > .content .olist > ol > li:last-child > :last-child, .exampleblock > .content .ulist > ul > li:last-child > :last-child, .exampleblock > .content .qlist > ol > li:last-child > :last-child, .sidebarblock > .content > :last-child > :last-child, .sidebarblock > .content .olist > ol > li:last-child > :last-child, .sidebarblock > .content .ulist > ul > li:last-child > :last-child, .sidebarblock > .content .qlist > ol > li:last-child > :last-child { margin-bottom: 0; } + +.literalblock pre:not([class]), .listingblock pre:not([class]) { background: #eeeeee; } +.literalblock pre, .literalblock pre[class], .listingblock pre, .listingblock pre[class] { border-width: 1px; border-style: solid; border-color: #cccccc; -webkit-border-radius: 6px; border-radius: 6px; padding: 0.5em; word-wrap: break-word; } +.literalblock pre.nowrap, .literalblock pre[class].nowrap, .listingblock pre.nowrap, .listingblock pre[class].nowrap { overflow-x: auto; white-space: pre; word-wrap: normal; } +.literalblock pre > code, .literalblock pre[class] > code, .listingblock pre > code, .listingblock pre[class] > code { display: block; } +@media only screen { .literalblock pre, .literalblock pre[class], .listingblock pre, .listingblock pre[class] { font-size: 0.76em; } } +@media only screen and (min-width: 768px) { .literalblock pre, .literalblock pre[class], .listingblock pre, .listingblock pre[class] { font-size: 0.855em; } } +@media only screen and (min-width: 1280px) { .literalblock pre, .literalblock pre[class], .listingblock pre, .listingblock pre[class] { font-size: 0.95em; } } + +.listingblock pre.highlight { padding: 0; } +.listingblock pre.highlight > code { padding: 0.5em; } + +.listingblock > .content { position: relative; } + +.listingblock:hover code[class*=" language-"]:before { text-transform: uppercase; font-size: 0.9em; color: #999; position: absolute; top: 0.375em; right: 0.375em; } + +.listingblock:hover code.asciidoc:before { content: "asciidoc"; } +.listingblock:hover code.clojure:before { content: "clojure"; } +.listingblock:hover code.css:before { content: "css"; } +.listingblock:hover code.groovy:before { content: "groovy"; } +.listingblock:hover code.html:before { content: "html"; } +.listingblock:hover code.java:before { content: "java"; } +.listingblock:hover code.javascript:before { content: "javascript"; } +.listingblock:hover code.python:before { content: "python"; } +.listingblock:hover code.ruby:before { content: "ruby"; } +.listingblock:hover code.sass:before { content: "sass"; } +.listingblock:hover code.scss:before { content: "scss"; } +.listingblock:hover code.xml:before { content: "xml"; } +.listingblock:hover code.yaml:before { content: "yaml"; } + +.listingblock.terminal pre .command:before { content: attr(data-prompt); padding-right: 0.5em; color: #999; } + +.listingblock.terminal pre .command:not([data-prompt]):before { content: '$'; } + +table.pyhltable { border: 0; margin-bottom: 0; } + +table.pyhltable td { vertical-align: top; padding-top: 0; padding-bottom: 0; } + +table.pyhltable td.code { padding-left: .75em; padding-right: 0; } + +.highlight.pygments .lineno, table.pyhltable td:not(.code) { color: #999; padding-left: 0; padding-right: .5em; border-right: 1px solid #dddddd; } + +.highlight.pygments .lineno { display: inline-block; margin-right: .25em; } + +table.pyhltable .linenodiv { background-color: transparent !important; padding-right: 0 !important; } + +.quoteblock { margin: 0 0 1.25em; padding: 0.5625em 1.25em 0 1.1875em; border-left: 1px solid #dddddd; } +.quoteblock blockquote { margin: 0 0 1.25em 0; padding: 0 0 0.5625em 0; border: 0; } +.quoteblock blockquote > .paragraph:last-child p { margin-bottom: 0; } +.quoteblock .attribution { margin-top: -.25em; padding-bottom: 0.5625em; font-size: 0.8125em; color: #748590; } +.quoteblock .attribution br { display: none; } +.quoteblock .attribution cite { display: block; margin-bottom: 0.625em; } + +table thead th, table tfoot th { font-weight: bold; } + +table.tableblock.grid-all { border-collapse: separate; border-spacing: 1px; -webkit-border-radius: 6px; border-radius: 6px; border-top: 0 solid #dddddd; border-bottom: 0 solid #dddddd; } + +table.tableblock.frame-topbot, table.tableblock.frame-none { border-left: 0; border-right: 0; } + +table.tableblock.frame-sides, table.tableblock.frame-none { border-top: 0; border-bottom: 0; } + +table.tableblock td .paragraph:last-child p > p:last-child, table.tableblock th > p:last-child, table.tableblock td > p:last-child { margin-bottom: 0; } + +th.tableblock.halign-left, td.tableblock.halign-left { text-align: left; } + +th.tableblock.halign-right, td.tableblock.halign-right { text-align: right; } + +th.tableblock.halign-center, td.tableblock.halign-center { text-align: center; } + +th.tableblock.valign-top, td.tableblock.valign-top { vertical-align: top; } + +th.tableblock.valign-bottom, td.tableblock.valign-bottom { vertical-align: bottom; } + +th.tableblock.valign-middle, td.tableblock.valign-middle { vertical-align: middle; } + +tbody tr th { display: table-cell; line-height: 1.5; background: none; } + +tbody tr th, tbody tr th p, tfoot tr th, tfoot tr th p { color: #222222; font-weight: bold; } + +td > div.verse { white-space: pre; } + +ol { margin-left: 0.25em; } + +ul li ol { margin-left: 0; } + +dl dd { margin-left: 1.125em; } + +dl dd:last-child, dl dd:last-child > :last-child { margin-bottom: 0; } + +ol > li p, ul > li p, ul dd, ol dd, .olist .olist, .ulist .ulist, .ulist .olist, .olist .ulist { margin-bottom: 0.625em; } + +ul.unstyled, ol.unnumbered, ul.checklist, ul.none { list-style-type: none; } + +ul.unstyled, ol.unnumbered, ul.checklist { margin-left: 0.625em; } + +ul.checklist li > p:first-child > i[class^="icon-check"]:first-child, ul.checklist li > p:first-child > input[type="checkbox"]:first-child { margin-right: 0.25em; } + +ul.checklist li > p:first-child > input[type="checkbox"]:first-child { position: relative; top: 1px; } + +ul.inline { margin: 0 auto 0.625em auto; margin-left: -1.375em; margin-right: 0; padding: 0; list-style: none; overflow: hidden; } +ul.inline > li { list-style: none; float: left; margin-left: 1.375em; display: block; } +ul.inline > li > * { display: block; } + +.unstyled dl dt { font-weight: normal; font-style: normal; } + +ol.arabic { list-style-type: decimal; } + +ol.decimal { list-style-type: decimal-leading-zero; } + +ol.loweralpha { list-style-type: lower-alpha; } + +ol.upperalpha { list-style-type: upper-alpha; } + +ol.lowerroman { list-style-type: lower-roman; } + +ol.upperroman { list-style-type: upper-roman; } + +ol.lowergreek { list-style-type: lower-greek; } + +.hdlist > table, .colist > table { border: 0; background: none; } +.hdlist > table > tbody > tr, .colist > table > tbody > tr { background: none; } + +td.hdlist1 { padding-right: .75em; font-weight: bold; } + +td.hdlist1, td.hdlist2 { vertical-align: top; } + +.literalblock + .colist, .listingblock + .colist { margin-top: -0.5em; } + +.colist > table tr > td:first-of-type { padding: 0 .75em; line-height: 1; } +.colist > table tr > td:last-of-type { padding: 0.25em 0; } + +.qanda > ol > li > p > em:only-child { color: #373737; } + +.thumb, .th { line-height: 0; display: inline-block; border: solid 4px white; -webkit-box-shadow: 0 0 0 1px #dddddd; box-shadow: 0 0 0 1px #dddddd; } + +.imageblock.left, .imageblock[style*="float: left"] { margin: 0.25em 0.625em 1.25em 0; } +.imageblock.right, .imageblock[style*="float: right"] { margin: 0.25em 0 1.25em 0.625em; } +.imageblock > .title { margin-bottom: 0; } +.imageblock.thumb, .imageblock.th { border-width: 6px; } +.imageblock.thumb > .title, .imageblock.th > .title { padding: 0 0.125em; } + +.image.left, .image.right { margin-top: 0.25em; margin-bottom: 0.25em; display: inline-block; line-height: 0; } +.image.left { margin-right: 0.625em; } +.image.right { margin-left: 0.625em; } + +a.image { text-decoration: none; } + +span.footnote, span.footnoteref { vertical-align: super; font-size: 0.875em; } +span.footnote a, span.footnoteref a { text-decoration: none; } + +#footnotes { padding-top: 0.75em; padding-bottom: 0.75em; margin-bottom: 0.625em; } +#footnotes hr { width: 20%; min-width: 6.25em; margin: -.25em 0 .75em 0; border-width: 1px 0 0 0; } +#footnotes .footnote { padding: 0 0.375em; line-height: 1.3; font-size: 0.875em; margin-left: 1.2em; text-indent: -1.2em; margin-bottom: .2em; } +#footnotes .footnote a:first-of-type { font-weight: bold; text-decoration: none; } +#footnotes .footnote:last-of-type { margin-bottom: 0; } + +#content #footnotes { margin-top: -0.625em; margin-bottom: 0; padding: 0.75em 0; } + +.gist .file-data > table { border: none; background: #fff; width: 100%; margin-bottom: 0; } +.gist .file-data > table td.line-data { width: 99%; } + +div.unbreakable { page-break-inside: avoid; } + +.big { font-size: larger; } + +.small { font-size: smaller; } + +.underline { text-decoration: underline; } + +.overline { text-decoration: overline; } + +.line-through { text-decoration: line-through; } + +.aqua { color: #00bfbf; } + +.aqua-background { background-color: #00fafa; } + +.black { color: black; } + +.black-background { background-color: black; } + +.blue { color: #0000bf; } + +.blue-background { background-color: #0000fa; } + +.fuchsia { color: #bf00bf; } + +.fuchsia-background { background-color: #fa00fa; } + +.gray { color: #606060; } + +.gray-background { background-color: #7d7d7d; } + +.green { color: #006000; } + +.green-background { background-color: #007d00; } + +.lime { color: #00bf00; } + +.lime-background { background-color: #00fa00; } + +.maroon { color: #600000; } + +.maroon-background { background-color: #7d0000; } + +.navy { color: #000060; } + +.navy-background { background-color: #00007d; } + +.olive { color: #606000; } + +.olive-background { background-color: #7d7d00; } + +.purple { color: #600060; } + +.purple-background { background-color: #7d007d; } + +.red { color: #bf0000; } + +.red-background { background-color: #fa0000; } + +.silver { color: #909090; } + +.silver-background { background-color: #bcbcbc; } + +.teal { color: #006060; } + +.teal-background { background-color: #007d7d; } + +.white { color: #bfbfbf; } + +.white-background { background-color: #fafafa; } + +.yellow { color: #bfbf00; } + +.yellow-background { background-color: #fafa00; } + +span.icon > [class^="icon-"], span.icon > [class*=" icon-"] { cursor: default; } + +.admonitionblock td.icon [class^="icon-"]:before { font-size: 2.5em; text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.5); cursor: default; } +.admonitionblock td.icon .icon-note:before { content: "\f05a"; color: #444444; color: #333333; } +.admonitionblock td.icon .icon-tip:before { content: "\f0eb"; text-shadow: 1px 1px 2px rgba(155, 155, 0, 0.8); color: #111; } +.admonitionblock td.icon .icon-warning:before { content: "\f071"; color: #bf6900; } +.admonitionblock td.icon .icon-caution:before { content: "\f06d"; color: #bf3400; } +.admonitionblock td.icon .icon-important:before { content: "\f06a"; color: #bf0000; } + +.conum { display: inline-block; color: white !important; background-color: black; -webkit-border-radius: 100px; border-radius: 100px; text-align: center; width: 20px; height: 20px; font-size: 12px; font-weight: bold; line-height: 20px; font-family: Arial, sans-serif; font-style: normal; position: relative; top: -2px; letter-spacing: -1px; } +.conum * { color: white !important; } +.conum + b { display: none; } +.conum:after { content: attr(data-value); } +.conum:not([data-value]):empty { display: none; } + +.listingblock code { white-space: pre; overflow: auto; overflow-wrap: normal; /* needed for webkit browsers */ } + +#toc ul.sectlevel0 > li > a { font-style: normal; font-weight: bold; } + +h4 { color: #6c818f; } + +.literalblock > .content > pre, .listingblock > .content > pre { -webkit-border-radius: 6px; border-radius: 6px; margin-left: 2em; margin-right: 2em; } + +.admonitionblock { margin-left: 2em; margin-right: 2em; } +.admonitionblock > table { border: 1px solid #609060; border-top-width: 1.5em; background-color: #e9ffe9; border-collapse: separate; -webkit-border-radius: 0; border-radius: 0; } +.admonitionblock > table td.icon { padding-top: .5em; padding-bottom: .5em; } +.admonitionblock > table td.content { padding: .5em 1em; color: black; font-size: .9em; border-left: none; } + +.sidebarblock { background-color: #e8ecef; border-color: #ccc; } +.sidebarblock > .content > .title { color: #444444; } + +table.tableblock.grid-all { border-collapse: collapse; -webkit-border-radius: 0; border-radius: 0; } +table.tableblock.grid-all th.tableblock, table.tableblock.grid-all td.tableblock { border-bottom: 1px solid #aaa; } + +#footer { background-color: #465158; padding: 2em; } + +#footer-text { color: #eee; font-size: 0.8em; text-align: center; } +</style> +<style> +/* Foundation stylesheet for CodeRay (to match GitHub theme) | MIT License | http://foundation.zurb.com */ +table.CodeRay { border-collapse: collapse; padding: 2px; margin-bottom: 0; border: 0; background: transparent; } +table.CodeRay td { padding: 0 .5em; vertical-align: top; } +table.CodeRay td.line-numbers { text-align: right; color: #999; border-right: 1px solid #e5e5e5; padding-left: 0; } +span.line-numbers { border-right: 1px solid #E5E5E5; color: #999; display: inline-block; margin-right: 0.5em; padding-right: 0.5em; } +.CodeRay td.line-numbers strong, .CodeRay span.line-numbers strong { font-weight: normal; } +.CodeRay .debug { color: white !important; background: blue !important; } +.CodeRay .annotation { color: #007; } +.CodeRay .attribute-name { color: #f08; } +.CodeRay .attribute-value { color: #700; } +.CodeRay .binary { color: #509; } +.CodeRay .comment { color: #999; font-style: italic; } +.CodeRay .char { color: #04D; } +.CodeRay .char .content { color: #04D; } +.CodeRay .char .delimiter { color: #039; } +.CodeRay .class { color: #458; } +.CodeRay .complex { color: #A08; } +.CodeRay .constant { color: teal; } +.CodeRay .color { color: #0A0; } +.CodeRay .class-variable { color: #369; } +.CodeRay .decorator { color: #B0B; } +.CodeRay .definition { color: #099; } +.CodeRay .directive { color: #088; } +.CodeRay .delimiter { color: black; } +.CodeRay .doc { color: #970; } +.CodeRay .doctype { color: #34b; } +.CodeRay .doc-string { color: #D42; } +.CodeRay .escape { color: #666; } +.CodeRay .entity { color: #800; } +.CodeRay .error { color: #808; } +.CodeRay .exception { color: #C00; } +.CodeRay .filename { color: #099; } +.CodeRay .function { color: #900; } +.CodeRay .global-variable { color: teal; } +.CodeRay .hex { color: #058; } +.CodeRay .integer { color: #099; } +.CodeRay .include { color: #B44; } +.CodeRay .inline { color: black; } +.CodeRay .inline .inline { background: #ccc; } +.CodeRay .inline .inline .inline { background: #bbb; } +.CodeRay .inline .inline-delimiter { color: #D14; } +.CodeRay .inline-delimiter { color: #D14; } +.CodeRay .important { color: #f00; } +.CodeRay .interpreted { color: #B2B; } +.CodeRay .instance-variable { color: teal; } +.CodeRay .label { color: #970; } +.CodeRay .local-variable { color: #963; } +.CodeRay .octal { color: #40E; } +.CodeRay .predefined { color: #369; } +.CodeRay .preprocessor { color: #579; } +.CodeRay .pseudo-class { color: #00C; } +.CodeRay .predefined-type { color: #074; } +.CodeRay .reserved, .keyword { color: #000; } +.CodeRay .key { color: #808; } +.CodeRay .key .delimiter { color: #606; } +.CodeRay .key .char { color: #80f; } +.CodeRay .value { color: #088; } +.CodeRay .regexp { background-color: #fff0ff; } +.CodeRay .regexp .content { color: #808; } +.CodeRay .regexp .delimiter { color: #404; } +.CodeRay .regexp .modifier { color: #C2C; } +.CodeRay .regexp .function { color: #404; font-weight: bold; } +.CodeRay .string { color: #D20; } +.CodeRay .string .string { } +.CodeRay .string .string .string { background-color: #ffd0d0; } +.CodeRay .string .content { color: #D14; } +.CodeRay .string .char { color: #D14; } +.CodeRay .string .delimiter { color: #D14; } +.CodeRay .shell { color: #D14; } +.CodeRay .shell .content { } +.CodeRay .shell .delimiter { color: #D14; } +.CodeRay .symbol { color: #990073; } +.CodeRay .symbol .content { color: #A60; } +.CodeRay .symbol .delimiter { color: #630; } +.CodeRay .tag, .CodeRay .attribute-name { color: #070; } +.CodeRay .tag-special { color: #D70; } +.CodeRay .type { color: #339; } +.CodeRay .variable { color: #036; } +.CodeRay .insert { background: #afa; } +.CodeRay .delete { background: #faa; } +.CodeRay .change { color: #aaf; background: #007; } +.CodeRay .head { color: #f8f; background: #505; } +.CodeRay .insert .insert { color: #080; } +.CodeRay .delete .delete { color: #800; } +.CodeRay .change .change { color: #66f; } +.CodeRay .head .head { color: #f4f; } + +</style> +</head> +<body class="article"> +<div id="header"> +</div> +<div id="content"> +<div class="imageblock"> +<div class="content"> +<a class="image" href="http://tinkerpop.apache.org";><img src="../../images/apache-tinkerpop-logo.png" alt="apache tinkerpop logo" width="500"></a> +</div> +</div> +<div class="paragraph"> +<p><strong>3.2.6-SNAPSHOT</strong></p> +</div> +<div class="sect1"> +<h2 id="_gremlin_language_variants">Gremlin Language Variants</h2> +<div class="sectionbody"> +<div class="paragraph"> +<p>Gremlin is an embeddable query language that can be represented using the constructs of a host programming language. +Any programming language that supports <a href="https://en.wikipedia.org/wiki/Function_composition";>function composition</a> +(e.g. fluent chaining) and <a href="https://en.wikipedia.org/wiki/Nested_function";>function nesting</a> (e.g. call stacks) +can support Gremlin. Nearly every modern programming language is capable of meeting both requirements. +With Gremlin, the distinction between a programming language and a query language is not as large as they +have historically been. For instance, with Gremlin-Java, the developer is able to have their application code and their +graph database queries at the same level of abstraction — both written in Java. A simple example is presented below +where the <code>MyApplication</code> Java class contains both application-level and database-level code written in Java.</p> +</div> +<div class="imageblock"> +<div class="content"> +<img src="../../images/gremlin-house-of-mirrors.png" alt="gremlin house of mirrors" width="1024"> +</div> +</div> +<div class="admonitionblock warning"> +<table> +<tr> +<td class="icon"> +<div class="title">Warning</div> +</td> +<td class="content"> +This is an advanced tutorial intended for experts knowledgeable in Gremlin in particular and TinkerPop in general. +Moreover, the audience should understand advanced programming language concepts such as reflection, meta-programming, +source code generation, and virtual machines. +</td> +</tr> +</table> +</div> +<div class="listingblock"> +<div class="content"> +<pre class="CodeRay"><code class="java language-java"><span class="directive">public</span> <span class="type">class</span> <span class="class">MyApplication</span> { + + <span class="directive">public</span> <span class="directive">static</span> <span class="type">void</span> run(<span class="directive">final</span> <span class="predefined-type">String</span><span class="type">[]</span> args) { + + <span class="comment">// assumes args[0] is a configuration file location</span> + Graph graph = GraphFactory.open(args[<span class="integer">0</span>]); + GraphTraversalSource g = graph.traversal(); + + <span class="comment">// assumes that args[1] and args[2] are range boundaries</span> + <span class="predefined-type">Iterator</span><<span class="predefined-type">Map</span><<span class="predefined-type">String</span>,<span class="predefined-type">Double</span>>> result = + g.V().hasLabel(<span class="string"><span class="delimiter">"</span><span class="content">product</span><span class="delimiter">"</span></span>). + order().by(<span class="string"><span class="delimiter">"</span><span class="content">unitPrice</span><span class="delimiter">"</span></span>, incr). + range(<span class="predefined-type">Integer</span>.valueOf(args[<span class="integer">1</span>]), <span class="predefined-type">Integer</span>.valueOf(args[<span class="integer">2</span>])). + valueMap(<span class="string"><span class="delimiter">"</span><span class="content">name</span><span class="delimiter">"</span></span>, <span class="string"><span class="delimiter">"</span><span class="content">unitPrice</span><span class="delimiter">"</span></span>) + + <span class="keyword">while</span>(result.hasNext()) { + <span class="predefined-type">Map</span><<span class="predefined-type">String</span>,<span class="predefined-type">Double</span>> map = result.next(); + <span class="predefined-type">System</span>.out.println(map.get(<span class="string"><span class="delimiter">"</span><span class="content">name</span><span class="delimiter">"</span></span>) + <span class="string"><span class="delimiter">"</span><span class="content"> </span><span class="delimiter">"</span></span> + map.get(<span class="string"><span class="delimiter">"</span><span class="content">unitPrice</span><span class="delimiter">"</span></span>)); + } + } +}</code></pre> +</div> +</div> +<div class="paragraph"> +<p>In query languages like <a href="https://en.wikipedia.org/wiki/SQL";>SQL</a>, the user must construct a string representation of +their query and submit it to the database for evaluation. This is because SQL cannot be expressed in Java as they use fundamentally +different constructs in their expression. The same example above is presented below using SQL and the +<a href="https://en.wikipedia.org/wiki/Java_Database_Connectivity";>JDBC</a> interface. The take home point is that Gremlin does +not exist outside the programming language in which it will be used. Gremlin was designed to be able to be +embedded in any modern programming language and thus, always free from the complexities of string manipulation as seen +in other database and analytics query languages.</p> +</div> +<div class="listingblock"> +<div class="content"> +<pre class="CodeRay"><code class="java language-java"><span class="directive">public</span> <span class="type">class</span> <span class="class">MyApplication</span> { + + <span class="directive">public</span> <span class="directive">static</span> <span class="type">void</span> run(<span class="directive">final</span> <span class="predefined-type">String</span><span class="type">[]</span> args) { + + <span class="comment">// assumes args[0] is a URI to the database</span> + <span class="predefined-type">Connection</span> connection = <span class="predefined-type">DriverManager</span>.getConnection(args[<span class="integer">0</span>]) + <span class="predefined-type">Statement</span> statement = connection.createStatement(); + + <span class="comment">// assumes that args[1] and args[2] are range boundaries</span> + <span class="predefined-type">ResultSet</span> result = statement.executeQuery( + <span class="string"><span class="delimiter">"</span><span class="content">SELECT Products.ProductName, Products.UnitPrice </span><span class="char">\n</span><span class="delimiter">"</span></span> + + <span class="string"><span class="delimiter">"</span><span class="content"> FROM (SELECT ROW_NUMBER() </span><span class="char">\n</span><span class="delimiter">"</span></span> + + <span class="string"><span class="delimiter">"</span><span class="content"> OVER ( </span><span class="char">\n</span><span class="delimiter">"</span></span> + + <span class="string"><span class="delimiter">"</span><span class="content"> ORDER BY UnitPrice) AS [ROW_NUMBER], </span><span class="char">\n</span><span class="delimiter">"</span></span> + + <span class="string"><span class="delimiter">"</span><span class="content"> ProductID </span><span class="char">\n</span><span class="delimiter">"</span></span> + + <span class="string"><span class="delimiter">"</span><span class="content"> FROM Products) AS SortedProducts </span><span class="char">\n</span><span class="delimiter">"</span></span> + + <span class="string"><span class="delimiter">"</span><span class="content"> INNER JOIN Products </span><span class="char">\n</span><span class="delimiter">"</span></span> + + <span class="string"><span class="delimiter">"</span><span class="content"> ON Products.ProductID = SortedProducts.ProductID </span><span class="char">\n</span><span class="delimiter">"</span></span> + + <span class="string"><span class="delimiter">"</span><span class="content"> WHERE [ROW_NUMBER] BETWEEN </span><span class="delimiter">"</span></span> + args[<span class="integer">1</span>] + <span class="string"><span class="delimiter">"</span><span class="content"> AND </span><span class="delimiter">"</span></span> + args[<span class="integer">2</span>] + <span class="string"><span class="delimiter">"</span><span class="content"> </span><span class="char">\n</span><span class="delimiter">"</span></span> + + <span class="string"><span class="delimiter">"</span><span class="content">ORDER BY [ROW_NUMBER]</span><span class="delimiter">"</span></span> + + <span class="keyword">while</span>(result.hasNext()) { + result.next(); + <span class="predefined-type">System</span>.out.println(result.getString(<span class="string"><span class="delimiter">"</span><span class="content">Products.ProductName</span><span class="delimiter">"</span></span>) + <span class="string"><span class="delimiter">"</span><span class="content"> </span><span class="delimiter">"</span></span> + result.getDouble(<span class="string"><span class="delimiter">"</span><span class="content">Products.UnitPrice</span><span class="delimiter">"</span></span>)); + } + } +}</code></pre> +</div> +</div> +<div class="paragraph"> +<p>The purpose of this tutorial is to explain how to develop a <em>Gremlin language variant</em>. That is, for those developers that +are interested in supporting Gremlin in their native language and there currently does not exist a (good) Gremlin variant in +their language, they can develop one for the Apache TinkerPop community (and their language community in general). In this +tutorial, <a href="https://www.python.org/";>Python</a> will serve as the host language and two typical implementation models will be presented.</p> +</div> +<div class="olist arabic"> +<ol class="arabic"> +<li> +<p><a href="#using-jython-and-the-jvm"><strong>Using Jython and the JVM</strong></a>: This is perhaps the easiest way to produce a Gremlin +language variant. With <a href="https://www.jcp.org/en/jsr/detail?id=223";>JSR-223</a>, any language compiler written for the JVM +can directly access the JVM and any of its libraries (including Gremlin-Java).</p> +</li> +<li> +<p><a href="#using-python-and-gremlin-server"><strong>Using Python and GremlinServer</strong></a>: This model requires that there exist a Python +class that mimics Gremlin-Java’s <code>GraphTraversal</code> API. With each method call of this Python class, Gremlin <code>Bytecode</code> is +generated which is ultimately translated into a Gremlin variant that can execute the traversal (e.g. Gremlin-Java).</p> +</li> +</ol> +</div> +<div class="admonitionblock important"> +<table> +<tr> +<td class="icon"> +<div class="title">Important</div> +</td> +<td class="content"> +Apache TinkerPop’s Gremlin-Java is considered the idiomatic, standard implementation of Gremlin. +Any Gremlin language variant, regardless of the implementation model chosen, <strong>must</strong>, within the constraints of the +host language, be in 1-to-1 correspondence with Gremlin-Java. This ensures that language variants are collectively +consistent and easily leveraged by anyone versed in Gremlin. +</td> +</tr> +</table> +</div> +<div class="admonitionblock important"> +<table> +<tr> +<td class="icon"> +<div class="title">Important</div> +</td> +<td class="content"> +The "Gremlin-Python" presented in this tutorial is basic and provided to show the primary techniques used to +construct a Gremlin language variant. Apache TinkerPop distributes with a full fledged Gremlin-Python variant +that uses many of the techniques presented in this tutorial. +</td> +</tr> +</table> +</div> +</div> +</div> +<div class="sect1"> +<h2 id="language-drivers-vs-language-variants">Language Drivers vs. Language Variants</h2> +<div class="sectionbody"> +<div class="paragraph"> +<p>Before discussing how to implement a Gremlin language variant in Python, it is necessary to understand two concepts related to +Gremlin language development. There is a difference between a <em>language driver</em> and a <em>language variant</em> and it is important +that these two concepts (and their respective implementations) remain separate.</p> +</div> +<div class="sect2"> +<h3 id="_language_drivers">Language Drivers</h3> +<div class="paragraph"> +<p><span class="image" style="float: right"><img src="../../images/language-drivers.png" alt="language-drivers" width="375"></span> A Gremlin language driver is a software library that is able to +communicate with a TinkerPop-enabled graph system whether directly via the JVM or indirectly via +<a href="http://tinkerpop.apache.org/docs/3.2.6-SNAPSHOT/reference/#gremlin-server";>Gremlin Server</a> GremlinServer or some other +<a href="http://tinkerpop.apache.org/docs/3.2.6-SNAPSHOT/reference/#connecting-via-remotegraph";>RemoteConnection</a> enabled graph system. +Language drivers are responsible for submitting Gremlin traversals to a TinkerPop-enabled graph system and +returning results to the developer that are within the developer’s language’s type system. +For instance, resultant doubles should be coerced to floats in Python.</p> +</div> +<div class="paragraph"> +<p>This tutorial is not about language drivers, but about language variants. Moreover, community libraries should make this +distinction clear and <strong>should not</strong> develop libraries that serve both roles. Language drivers will be useful to a collection +of Gremlin variants within a language community — able to support <code>GraphTraversal</code>-variants as well as also other +<a href="https://en.wikipedia.org/wiki/Domain-specific_language";>DSL</a>-variants (e.g. <code>SocialTraversal</code>).</p> +</div> +<div class="admonitionblock note"> +<table> +<tr> +<td class="icon"> +<div class="title">Note</div> +</td> +<td class="content"> +<code>GraphTraversal</code> is a particular Gremlin domain-specific language (<a href="https://en.wikipedia.org/wiki/Domain-specific_language";>DSL</a>), +albeit the most popular and foundational DSL. If another DSL is created, then the same techniques discussed in this tutorial +for <code>GraphTraversal</code> apply to <code>XXXTraversal</code>. +</td> +</tr> +</table> +</div> +</div> +<div class="sect2"> +<h3 id="_language_variants">Language Variants</h3> +<div class="paragraph"> +<p><span class="image" style="float: right"><img src="../../images/language-variants.png" alt="language-variants" width="375"></span> A Gremlin language variant is a software library that allows a developer +to write a Gremlin traversal within their native programming language. The language variant is responsible for +creating Gremlin <code>Bytecode</code> that will ultimately be translated and compiled to a <code>Traversal</code> by a TinkerPop-enabled graph system.</p> +</div> +<div class="paragraph"> +<p>Every language variant, regardless of the implementation details, will have to account for the four core concepts below:</p> +</div> +<div class="olist arabic"> +<ol class="arabic"> +<li> +<p><code>Graph</code> (<strong>data</strong>): The source of the graph data to be traversed and the interface which enables the creation of a +<code>GraphTraversalSource</code> (via <code>graph.traversal()</code>).</p> +</li> +<li> +<p><code>GraphTraversalSource</code> (<strong>compiler</strong>): This is the typical <code>g</code> reference. A <code>GraphTraversalSource</code> maintains the +<code>withXXX()</code>-strategy methods as well as the "traversal spawn"-methods such as <code>V()</code>, <code>E()</code>, <code>addV()</code>, etc. +A traversal source’s registered <code>TraversalStrategies</code> determine how the submitted traversal will be ultimately evaluated.</p> +</li> +<li> +<p><code>GraphTraversal</code> (<strong>function composition</strong>): A graph traversal maintains the computational steps such as <code>out()</code>, <code>groupCount()</code>, +<code>match()</code>, etc. This fluent interface supports method chaining and thus, a linear "left-to-right" representation of a traversal/query.</p> +</li> +<li> +<p><code>__</code> (<strong>function nesting</strong>) : The anonymous traversal class is used for passing a traversal as an argument to a parent step. +For example, in <code>repeat(__.out())</code>, <code>__.out()</code> is an anonymous traversal passed to the traversal parent <code>repeat()</code>. +Anonymous traversals enable the "top-to-bottom" representation of a traversal.</p> +</li> +<li> +<p><code>Bytecode</code> (<strong>language agnostic encoding</strong>): The source and traversal steps and their arguments are encoded in a +language agnostic representation called Gremlin bytecode. This representation is a nested list of the form <code>[step,[args*]]*</code>.</p> +</li> +</ol> +</div> +<div class="paragraph"> +<p>Both <code>GraphTraversal</code> and <code>__</code> define the structure of the Gremlin language. Gremlin is a <em>two-dimensional language</em> supporting +linear, nested step sequences. Historically, many Gremlin language variants have failed to make the distinctions above clear +and in doing so, either complicate their implementations or yield variants that are not in 1-to-1 correspondence with Gremlin-Java. +By keeping these concepts clear when designing a language variant, the construction of the Gremlin bytecode representation is +easy.</p> +</div> +<div class="admonitionblock important"> +<table> +<tr> +<td class="icon"> +<div class="title">Important</div> +</td> +<td class="content"> +The term "Gremlin-Java" denotes the language that is defined by <code>GraphTraversalSource</code>, <code>GraphTraversal</code>, +and <code>__</code>. These three classes exist in <code>org.apache.tinkerpop.gremlin.process.traversal.dsl.graph</code> and form the definitive +representation of the Gremlin traversal language. +</td> +</tr> +</table> +</div> +</div> +</div> +</div> +<div class="sect1"> +<h2 id="_gremlin_jython_and_gremlin_python">Gremlin-Jython and Gremlin-Python</h2> +<div class="sectionbody"> +<div class="sect2"> +<h3 id="using-jython-and-the-jvm">Using Jython and the JVM</h3> +<div class="paragraph"> +<p><span class="image" style="float: left"><a class="image" href="http://www.jython.org/";><img src="../../images/jython-logo.png" alt="jython-logo" width="200"></a></span> <a href="http://www.jython.org/";>Jython</a> provides a +<a href="https://www.jcp.org/en/jsr/detail?id=223";>JSR-223</a> <code>ScriptEngine</code> implementation that enables the evaluation of +Python on the <a href="https://en.wikipedia.org/wiki/Java_virtual_machine";>Java virtual machine</a>. In other words, Jython’s +virtual machine is not the standard <a href="https://wiki.python.org/moin/CPython";>CPython</a> reference implementation +distributed with most operating systems, but instead the JVM. The benefit of Jython is that Python code and classes +can easily interact with the Java API and any Java packages on the <code>CLASSPATH</code>. In general, any JSR-223 Gremlin language +variant is trivial to "implement."</p> +</div> +<div class="listingblock"> +<div class="content"> +<pre class="CodeRay"><code class="python language-python">Jython <span class="float">2.7</span><span class="float">.0</span> (default:<span class="integer">9987</span>c746f838, Apr <span class="integer">29</span> <span class="integer">2015</span>, <span class="octal">02</span>:<span class="integer">25</span>:<span class="integer">11</span>) +[Java HotSpot(TM) <span class="integer">64</span>-Bit Server VM (Oracle Corporation)] on java1<span class="float">.8</span><span class="float">.0</span>_40 +Type <span class="string"><span class="delimiter">"</span><span class="content">help</span><span class="delimiter">"</span></span>, <span class="string"><span class="delimiter">"</span><span class="content">copyright</span><span class="delimiter">"</span></span>, <span class="string"><span class="delimiter">"</span><span class="content">credits</span><span class="delimiter">"</span></span> <span class="keyword">or</span> <span class="string"><span class="delimiter">"</span><span class="content">license</span><span class="delimiter">"</span></span> <span class="keyword">for</span> more information. +>>> <span class="keyword">import</span> <span class="include">sys</span> +<span class="comment"># this list is longer than displayed, including all jars in lib/, not just Apache TinkerPop jars</span> +<span class="comment"># there is probably a more convenient way of importing jars in Jython though, at the time of writing, no better solution was found.</span> +>>> sys.path.append(<span class="string"><span class="delimiter">"</span><span class="content">/usr/local/apache-gremlin-console-3.2.6-SNAPSHOT-standalone/lib/gremlin-console-3.2.6-SNAPSHOT.jar</span><span class="delimiter">"</span></span>) +>>> sys.path.append(<span class="string"><span class="delimiter">"</span><span class="content">/usr/local/apache-gremlin-console-3.2.6-SNAPSHOT-standalone/lib/gremlin-core-3.2.6-SNAPSHOT.jar</span><span class="delimiter">"</span></span>) +>>> sys.path.append(<span class="string"><span class="delimiter">"</span><span class="content">/usr/local/apache-gremlin-console-3.2.6-SNAPSHOT-standalone/lib/gremlin-driver-3.2.6-SNAPSHOT.jar</span><span class="delimiter">"</span></span>) +>>> sys.path.append(<span class="string"><span class="delimiter">"</span><span class="content">/usr/local/apache-gremlin-console-3.2.6-SNAPSHOT-standalone/lib/gremlin-shaded-3.2.6-SNAPSHOT.jar</span><span class="delimiter">"</span></span>) +>>> sys.path.append(<span class="string"><span class="delimiter">"</span><span class="content">/usr/local/apache-gremlin-console-3.2.6-SNAPSHOT-standalone/ext/tinkergraph-gremlin/lib/tinkergraph-gremlin-3.2.6-SNAPSHOT.jar</span><span class="delimiter">"</span></span>) +<span class="comment"># import Java classes</span> +>>> <span class="keyword">from</span> <span class="include">org.apache.tinkerpop.gremlin.tinkergraph.structure</span> <span class="keyword">import</span> <span class="include">TinkerFactory</span> +>>> <span class="keyword">from</span> <span class="include">org.apache.tinkerpop.gremlin.process.traversal.dsl.graph</span> <span class="keyword">import</span> <span class="include">__</span> +>>> <span class="keyword">from</span> <span class="include">org.apache.tinkerpop.gremlin.process.traversal</span> <span class="keyword">import</span> <span class="include">*</span> +>>> <span class="keyword">from</span> <span class="include">org.apache.tinkerpop.gremlin.structure</span> <span class="keyword">import</span> <span class="include">*</span> +<span class="comment"># create the toy "modern" graph and spawn a GraphTraversalSource</span> +>>> graph = TinkerFactory.createModern() +>>> g = graph.traversal() +<span class="comment"># The Jython shell does not automatically iterate Iterators like the GremlinConsole</span> +>>> g.V().hasLabel(<span class="string"><span class="delimiter">"</span><span class="content">person</span><span class="delimiter">"</span></span>).out(<span class="string"><span class="delimiter">"</span><span class="content">knows</span><span class="delimiter">"</span></span>).out(<span class="string"><span class="delimiter">"</span><span class="content">created</span><span class="delimiter">"</span></span>) +[GraphStep(vertex,[]), HasStep([~label.eq(person)]), VertexStep(OUT,[knows],vertex), VertexStep(OUT,[created],vertex)] +<span class="comment"># toList() will do the iteration and return the results as a list</span> +>>> g.V().hasLabel(<span class="string"><span class="delimiter">"</span><span class="content">person</span><span class="delimiter">"</span></span>).out(<span class="string"><span class="delimiter">"</span><span class="content">knows</span><span class="delimiter">"</span></span>).out(<span class="string"><span class="delimiter">"</span><span class="content">created</span><span class="delimiter">"</span></span>).toList() +[v[<span class="integer">5</span>], v[<span class="integer">3</span>]] +>>> g.V().repeat(__.out()).times(<span class="integer">2</span>).values(<span class="string"><span class="delimiter">"</span><span class="content">name</span><span class="delimiter">"</span></span>).toList() +[ripple, lop] +<span class="comment"># results can be interacted with using Python</span> +>>> g.V().repeat(__.out()).times(<span class="integer">2</span>).values(<span class="string"><span class="delimiter">"</span><span class="content">name</span><span class="delimiter">"</span></span>).toList()[<span class="integer">0</span>] +<span class="string"><span class="modifier">u</span><span class="delimiter">'</span><span class="content">ripple</span><span class="delimiter">'</span></span> +>>> g.V().repeat(__.out()).times(<span class="integer">2</span>).values(<span class="string"><span class="delimiter">"</span><span class="content">name</span><span class="delimiter">"</span></span>).toList()[<span class="integer">0</span>][<span class="integer">0</span>:<span class="integer">3</span>].upper() +<span class="string"><span class="modifier">u</span><span class="delimiter">'</span><span class="content">RIP</span><span class="delimiter">'</span></span> +>>></code></pre> +</div> +</div> +<div class="paragraph"> +<p>Most every JSR-223 <code>ScriptEngine</code> language will allow the developer to immediately interact with <code>GraphTraversal</code>. +The benefit of this model is that nearly every major programming language has a respective <code>ScriptEngine</code>: +<a href="https://en.wikipedia.org/wiki/Nashorn_(JavaScript_engine)">JavaScript</a>, <a href="http://groovy-lang.org/";>Groovy</a>, +<a href="http://www.scala-lang.org/";>Scala</a>, Lisp (<a href="https://clojure.org/";>Clojure</a>), <a href="http://jruby.org/";>Ruby</a>, etc. A +list of implementations is provided <a href="https://en.wikipedia.org/wiki/List_of_JVM_languages";>here</a>.</p> +</div> +<div class="sect3"> +<h4 id="_traversal_wrappers">Traversal Wrappers</h4> +<div class="paragraph"> +<p>While it is possible to simply interact with Java classes in a <code>ScriptEngine</code> implementation, such Gremlin language variants +will not leverage the unique features of the host language. It is for this reason that JVM-based language variants such as +<a href="https://github.com/mpollmeier/gremlin-scala";>Gremlin-Scala</a> were developed. Scala provides many syntax niceties not +available in Java. To leverage these niceties, Gremlin-Scala "wraps" <code>GraphTraversal</code> in order to provide Scala-idiomatic extensions. +Another example is Apache TinkerPop’s Gremlin-Groovy which does the same via the +<a href="http://tinkerpop.apache.org/docs/3.2.6-SNAPSHOT/reference/#sugar-plugin";>Sugar plugin</a>, but uses +<a href="http://groovy-lang.org/metaprogramming.html";>meta-programming</a> instead of object wrapping, where "behind the scenes," +Groovy meta-programming is doing object wrapping.</p> +</div> +<div class="paragraph"> +<p>The Jython example below uses Python meta-programming to add functionality to <code>GraphTraversal</code>. +In particular, the <code>__getitem__</code> and <code>__getattr__</code> "magic methods" are leveraged.</p> +</div> +<div class="listingblock"> +<div class="content"> +<pre class="CodeRay"><code class="python language-python"><span class="keyword">def</span> <span class="function">getitem_bypass</span>(<span class="predefined-constant">self</span>, index): + <span class="keyword">if</span> <span class="predefined">isinstance</span>(index,<span class="predefined">int</span>): + <span class="keyword">return</span> <span class="predefined-constant">self</span>.range(index,index+<span class="integer">1</span>) + <span class="keyword">elif</span> <span class="predefined">isinstance</span>(index,<span class="predefined">slice</span>): + <span class="keyword">return</span> <span class="predefined-constant">self</span>.range(index.start,index.stop) + <span class="keyword">else</span>: + <span class="keyword">return</span> <span class="exception">TypeError</span>(<span class="string"><span class="delimiter">'</span><span class="content">Index must be int or slice</span><span class="delimiter">'</span></span>)<span class="string"><span class="delimiter">"</span><span class="content">);</span></span> +GraphTraversal.__getitem__ = getitem_bypass +GraphTraversal.__getattr__ = <span class="keyword">lambda</span> <span class="predefined-constant">self</span>, key: <span class="predefined-constant">self</span>.values(key)</code></pre> +</div> +</div> +<div class="paragraph"> +<p>The two methods <code>__getitem__</code> and <code>__getattr__</code> support Python <em>slicing</em> and <em>object attribute interception</em>, respectively. +In this way, the host language is able to use its native constructs in a meaningful way within a Gremlin traversal.</p> +</div> +<div class="admonitionblock important"> +<table> +<tr> +<td class="icon"> +<div class="title">Important</div> +</td> +<td class="content"> +Gremlin-Java serves as the standard/default representation of the Gremlin traversal language. Any Gremlin +language variant <strong>must</strong> provide all the same functionality (methods) as <code>GraphTraversal</code>, but <strong>can</strong> extend it +with host language specific constructs. This means that the extensions <strong>must</strong> compile to <code>GraphTraversal</code>-specific +steps. A Gremlin language variant <strong>should not</strong> add steps/methods that do not exist in <code>GraphTraversal</code>. If an extension +is desired, the language variant designer should submit a proposal to <a href="http://tinkerpop.apache.org";>Apache TinkerPop</a> +to have the extension added to a future release of Gremlin. +</td> +</tr> +</table> +</div> +</div> +</div> +<div class="sect2"> +<h3 id="using-python-and-remoteconnection">Using Python and RemoteConnection</h3> +<div class="paragraph"> +<p><span class="image" style="float: left"><a class="image" href="https://www.python.org/";><img src="../../images/python-logo.png" alt="python-logo" width="125"></a></span> The JVM is a powerful piece of technology that has, over the years, +become a meeting ground for developers from numerous language communities. However, not all applications will use the JVM. +Given that Apache TinkerPop is a Java-framework, there must be a way for two different virtual machines to communicate +traversals and their results. This section presents the second Gremlin language variant implementation model which does just that.</p> +</div> +<div class="admonitionblock note"> +<table> +<tr> +<td class="icon"> +<div class="title">Note</div> +</td> +<td class="content"> +Apache TinkerPop is a JVM-based graph computing framework. Most graph databases and processors today are built +on the JVM. This makes it easy for these graph system providers to implement Apache TinkerPop. However, TinkerPop is more +than its graph API and tools — it is also the Gremlin traversal machine and language. While Apache’s Gremlin traversal +machine was written for the JVM, its constructs are simple and can/should be ported to other VMs for those graph systems +that are not JVM-based. A theoretical review of the concepts behind the Gremlin traversal machine is provided in +<a href="http://arxiv.org/abs/1508.03843";>this article</a>. +</td> +</tr> +</table> +</div> +<div class="paragraph"> +<p>This section’s Gremlin language variant design model does not leverage the JVM directly. Instead, it constructs a <code>Bytecode</code> +representation of a <code>Traversal</code> that will ultimately be evaluated by <code>RemoteConnection</code> (e.g. GremlinServer). +It is up to the language variant designer to choose a <em>language driver</em> to use for submitting the generated bytecode and +coercing its results. The language driver is the means by which, for this example, the CPython +VM communicates with the JVM.</p> +</div> +<div class="listingblock"> +<div class="content"> +<pre class="CodeRay"><code class="bash language-bash"># sudo easy_install pip +$ pip install gremlinpython</code></pre> +</div> +</div> +<div class="paragraph"> +<p>The Groovy source code below uses Java reflection to generate a Python class that is in 1-to-1 correspondence with +Gremlin-Java.</p> +</div> +<div class="listingblock"> +<div class="content"> +<pre class="CodeRay"><code class="groovy language-groovy"><span class="type">class</span> <span class="class">GraphTraversalSourceGenerator</span> { + + <span class="directive">public</span> <span class="directive">static</span> <span class="type">void</span> create(<span class="directive">final</span> <span class="predefined-type">String</span> graphTraversalSourceFile) { + + <span class="directive">final</span> <span class="predefined-type">StringBuilder</span> pythonClass = <span class="keyword">new</span> <span class="predefined-type">StringBuilder</span>() + + pythonClass.append(<span class="string"><span class="delimiter">"</span><span class="content">from .traversal import Traversal</span><span class="char">\n</span><span class="delimiter">"</span></span>) + pythonClass.append(<span class="string"><span class="delimiter">"</span><span class="content">from .traversal import TraversalStrategies</span><span class="char">\n</span><span class="delimiter">"</span></span>) + pythonClass.append(<span class="string"><span class="delimiter">"</span><span class="content">from .traversal import Bytecode</span><span class="char">\n</span><span class="delimiter">"</span></span>) + pythonClass.append(<span class="string"><span class="delimiter">"</span><span class="content">from ..driver.remote_connection import RemoteStrategy</span><span class="char">\n</span><span class="delimiter">"</span></span>) + pythonClass.append(<span class="string"><span class="delimiter">"</span><span class="content">from .. import statics</span><span class="char">\n</span><span class="char">\n</span><span class="delimiter">"</span></span>) + +<span class="comment">//////////////////////////</span> +<span class="comment">// GraphTraversalSource //</span> +<span class="comment">//////////////////////////</span> + pythonClass.append( + <span class="string"><span class="delimiter">"""</span><span class="content">class GraphTraversalSource(object): + def __init__(self, graph, traversal_strategies, bytecode=None): + self.graph = graph + self.traversal_strategies = traversal_strategies + if bytecode is None: + bytecode = Bytecode() + self.bytecode = bytecode + def __repr__(self): + return "graphtraversalsource[" + str(self.graph) + "]" +</span><span class="delimiter">"""</span></span>) + GraphTraversalSource.getMethods(). <span class="comment">// SOURCE STEPS</span> + findAll { GraphTraversalSource.class.equals(<span class="local-variable">it</span>.returnType) }. + findAll { + !<span class="local-variable">it</span>.name.equals(<span class="string"><span class="delimiter">"</span><span class="content">clone</span><span class="delimiter">"</span></span>) && + !<span class="local-variable">it</span>.name.equals(TraversalSource.Symbols.withRemote) + }. + collect { SymbolHelper.toPython(<span class="local-variable">it</span>.name) }. + unique(). + sort { a, b -> a <=> b }. + forEach { method -> + pythonClass.append( + <span class="string"><span class="delimiter">"""</span><span class="content"> def </span><span class="inline"><span class="inline-delimiter">${</span>method<span class="inline-delimiter">}</span></span><span class="content">(self, *args): + source = GraphTraversalSource(self.graph, TraversalStrategies(self.traversal_strategies), Bytecode(self.bytecode)) + source.bytecode.add_source("</span><span class="inline"><span class="inline-delimiter">${</span>SymbolHelper.toJava(method)<span class="inline-delimiter">}</span></span><span class="content">", *args) + return source +</span><span class="delimiter">"""</span></span>) + } + pythonClass.append( + <span class="string"><span class="delimiter">"""</span><span class="content"> def withRemote(self, remote_connection): + source = GraphTraversalSource(self.graph, TraversalStrategies(self.traversal_strategies), Bytecode(self.bytecode)) + source.traversal_strategies.add_strategies([RemoteStrategy(remote_connection)]) + return source +</span><span class="delimiter">"""</span></span>) + GraphTraversalSource.getMethods(). <span class="comment">// SPAWN STEPS</span> + findAll { GraphTraversal.class.equals(<span class="local-variable">it</span>.returnType) }. + collect { SymbolHelper.toPython(<span class="local-variable">it</span>.name) }. + unique(). + sort { a, b -> a <=> b }. + forEach { method -> + pythonClass.append( + <span class="string"><span class="delimiter">"""</span><span class="content"> def </span><span class="inline"><span class="inline-delimiter">${</span>method<span class="inline-delimiter">}</span></span><span class="content">(self, *args): + traversal = GraphTraversal(self.graph, self.traversal_strategies, Bytecode(self.bytecode)) + traversal.bytecode.add_step("</span><span class="inline"><span class="inline-delimiter">${</span>SymbolHelper.toJava(method)<span class="inline-delimiter">}</span></span><span class="content">", *args) + return traversal +</span><span class="delimiter">"""</span></span>) + } + pythonClass.append(<span class="string"><span class="delimiter">"</span><span class="char">\n</span><span class="char">\n</span><span class="delimiter">"</span></span>) + +<span class="comment">////////////////////</span> +<span class="comment">// GraphTraversal //</span> +<span class="comment">////////////////////</span> + pythonClass.append( + <span class="string"><span class="delimiter">"""</span><span class="content">class GraphTraversal(Traversal): + def __init__(self, graph, traversal_strategies, bytecode): + Traversal.__init__(self, graph, traversal_strategies, bytecode) + def __getitem__(self, index): + if isinstance(index, int): + return self.range(index, index + 1) + elif isinstance(index, slice): + return self.range(index.start, index.stop) + else: + raise TypeError("Index must be int or slice") + def __getattr__(self, key): + return self.values(key) +</span><span class="delimiter">"""</span></span>) + GraphTraversal.getMethods(). + findAll { GraphTraversal.class.equals(<span class="local-variable">it</span>.returnType) }. + findAll { !<span class="local-variable">it</span>.name.equals(<span class="string"><span class="delimiter">"</span><span class="content">clone</span><span class="delimiter">"</span></span>) }. + collect { SymbolHelper.toPython(<span class="local-variable">it</span>.name) }. + unique(). + sort { a, b -> a <=> b }. + forEach { method -> + pythonClass.append( + <span class="string"><span class="delimiter">"""</span><span class="content"> def </span><span class="inline"><span class="inline-delimiter">${</span>method<span class="inline-delimiter">}</span></span><span class="content">(self, *args): + self.bytecode.add_step("</span><span class="inline"><span class="inline-delimiter">${</span>SymbolHelper.toJava(method)<span class="inline-delimiter">}</span></span><span class="content">", *args) + return self +</span><span class="delimiter">"""</span></span>) + }; + pythonClass.append(<span class="string"><span class="delimiter">"</span><span class="char">\n</span><span class="char">\n</span><span class="delimiter">"</span></span>) + +<span class="comment">////////////////////////</span> +<span class="comment">// AnonymousTraversal //</span> +<span class="comment">////////////////////////</span> + pythonClass.append(<span class="string"><span class="delimiter">"</span><span class="content">class __(object):</span><span class="char">\n</span><span class="delimiter">"</span></span>); + __.class.getMethods(). + findAll { GraphTraversal.class.equals(<span class="local-variable">it</span>.returnType) }. + findAll { <span class="predefined-type">Modifier</span>.isStatic(<span class="local-variable">it</span>.getModifiers()) }. + collect { SymbolHelper.toPython(<span class="local-variable">it</span>.name) }. + unique(). + sort { a, b -> a <=> b }. + forEach { method -> + pythonClass.append( + <span class="string"><span class="delimiter">"""</span><span class="content"> @staticmethod + def </span><span class="inline"><span class="inline-delimiter">${</span>method<span class="inline-delimiter">}</span></span><span class="content">(*args): + return GraphTraversal(None, None, Bytecode()).</span><span class="inline"><span class="inline-delimiter">${</span>method<span class="inline-delimiter">}</span></span><span class="content">(*args) +</span><span class="delimiter">"""</span></span>) + }; + pythonClass.append(<span class="string"><span class="delimiter">"</span><span class="char">\n</span><span class="char">\n</span><span class="delimiter">"</span></span>) + <span class="comment">// add to gremlin.python.statics</span> + __.class.getMethods(). + findAll { GraphTraversal.class.equals(<span class="local-variable">it</span>.returnType) }. + findAll { <span class="predefined-type">Modifier</span>.isStatic(<span class="local-variable">it</span>.getModifiers()) }. + findAll { !<span class="local-variable">it</span>.name.equals(<span class="string"><span class="delimiter">"</span><span class="content">__</span><span class="delimiter">"</span></span>) }. + collect { SymbolHelper.toPython(<span class="local-variable">it</span>.name) }. + unique(). + sort { a, b -> a <=> b }. + forEach { + pythonClass.append(<span class="string"><span class="delimiter">"</span><span class="content">def </span><span class="inline"><span class="inline-delimiter">${</span><span class="local-variable">it</span><span class="inline-delimiter">}</span></span><span class="content">(*args):</span><span class="char">\n</span><span class="delimiter">"</span></span>).append(<span class="string"><span class="delimiter">"</span><span class="content"> return __.</span><span class="inline"><span class="inline-delimiter">${</span><span class="local-variable">it</span><span class="inline-delimiter">}</span></span><span class="content">(*args)</span><span class="char">\n</span><span class="char">\n</span><span class="delimiter">"</span></span>) + pythonClass.append(<span class="string"><span class="delimiter">"</span><span class="content">statics.add_static('</span><span class="inline"><span class="inline-delimiter">${</span><span class="local-variable">it</span><span class="inline-delimiter">}</span></span><span class="content">', </span><span class="inline"><span class="inline-delimiter">${</span><span class="local-variable">it</span><span class="inline-delimiter">}</span></span><span class="content">)</span><span class="char">\n</span><span class="char">\n</span><span class="delimiter">"</span></span>) + } + pythonClass.append(<span class="string"><span class="delimiter">"</span><span class="char">\n</span><span class="char">\n</span><span class="delimiter">"</span></span>) + +<span class="comment">// save to a python file</span> + <span class="directive">final</span> <span class="predefined-type">File</span> file = <span class="keyword">new</span> <span class="predefined-type">File</span>(graphTraversalSourceFile); + file.delete() + pythonClass.eachLine { file.append(<span class="local-variable">it</span> + <span class="string"><span class="delimiter">"</span><span class="char">\n</span><span class="delimiter">"</span></span>) } + } +}</code></pre> +</div> +</div> +<div class="paragraph"> +<p>When the above Groovy script is evaluated (e.g. in GremlinConsole), <strong>Gremlin-Python</strong> is born. The generated Python +file is available at <a href="https://github.com/apache/tinkerpop/blob/3.2.6-SNAPSHOT/gremlin-python/src/main/jython/gremlin_python/process/graph_traversal.py";>graph_traversal.py</a>. +It is important to note that there is a bit more to Gremlin-Python in that there also exists Python implementations of <code>TraversalStrategies</code>, <code>Traversal</code>, <code>Bytecode</code>, etc. +Please review the full implementation of Gremlin-Python <a href="https://github.com/apache/tinkerpop/tree/3.2.6-SNAPSHOT/gremlin-python/src/main/jython/gremlin_python";>here</a>.</p> +</div> +<div class="admonitionblock note"> +<table> +<tr> +<td class="icon"> +<div class="title">Note</div> +</td> +<td class="content">
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