pskevin commented on a change in pull request #12445:
URL: https://github.com/apache/beam/pull/12445#discussion_r465370908
##########
File path: sdks/go/examples/xlang/wordcount/xlang_wordcount.go
##########
@@ -0,0 +1,100 @@
+package main
+
+import (
+ "context"
+ "flag"
+ "fmt"
+ "log"
+ "regexp"
+ "strings"
+
+ "github.com/apache/beam/sdks/go/pkg/beam/core/typex"
+ "github.com/apache/beam/sdks/go/pkg/beam/core/util/reflectx"
+
+ "github.com/apache/beam/sdks/go/pkg/beam"
+ "github.com/apache/beam/sdks/go/pkg/beam/io/textio"
+ "github.com/apache/beam/sdks/go/pkg/beam/x/beamx"
+
+ // Imports to enable correct filesystem access and runner setup in
LOOPBACK mode
+ _ "github.com/apache/beam/sdks/go/pkg/beam/io/filesystem/gcs"
+ _ "github.com/apache/beam/sdks/go/pkg/beam/io/filesystem/local"
+ _ "github.com/apache/beam/sdks/go/pkg/beam/runners/universal"
+)
+
+var (
+ // Set this option to choose a different input file or glob.
+ input = flag.String("input", "./input", "File(s) to read.")
+
+ // Set this required option to specify where to write the output.
+ output = flag.String("output", "./output", "Output file (required).")
+)
+
+var (
+ wordRE = regexp.MustCompile(`[a-zA-Z]+('[a-z])?`)
+ empty = beam.NewCounter("extract", "emptyLines")
+ lineLen = beam.NewDistribution("extract", "lineLenDistro")
+)
+
+// extractFn is a DoFn that emits the words in a given line.
+func extractFn(ctx context.Context, line string, emit func(string)) {
+ lineLen.Update(ctx, int64(len(line)))
+ if len(strings.TrimSpace(line)) == 0 {
+ empty.Inc(ctx, 1)
+ }
+ for _, word := range wordRE.FindAllString(line, -1) {
+ emit(word)
+ }
+}
+
+// formatFn is a DoFn that formats a word and its count as a string.
+func formatFn(w string, c int64) string {
+ fmt.Println(w, c)
+ return fmt.Sprintf("%s: %v", w, c)
+}
+
+func init() {
+ beam.RegisterFunction(extractFn)
+ beam.RegisterFunction(formatFn)
+}
+
+func main() {
+ // If beamx or Go flags are used, flags must be parsed first.
+ flag.Parse()
+ // beam.Init() is an initialization hook that must be called on
startup. On
+ // distributed runners, it is used to intercept control.
+ beam.Init()
+
+ // Input validation is done as usual. Note that it must be after Init().
+ if *output == "" {
+ log.Fatal("No output provided")
+ }
+
+ // Concepts #3 and #4: The pipeline uses the named transform and DoFn.
+ p := beam.NewPipeline()
+ s := p.Root()
+
+ lines := textio.Read(s, *input)
+ // Convert lines of text into individual words.
+ col := beam.ParDo(s, extractFn, lines)
+
+ // Using Cross-language Count from Python's test expansion service
+ // TODO(pskevin): Cleaner using-face API
+ outputType := typex.NewKV(typex.New(reflectx.String),
typex.New(reflectx.Int64))
+ external := &beam.ExternalTransform{
+ In: []beam.PCollection{col},
+ Urn: "beam:transforms:xlang:count",
+ ExpansionAddr: "localhost:8118",
+ Out: []typex.FullType{outputType},
+ Bounded: true, // TODO(pskevin): Infer this value from
output PCollection(s) part of the expanded tranform
+ }
+ counted := beam.CrossLanguage(s, p, external) // TODO(pskevin): Add
external transform to Pipeline without passing it to the transform
+
+ formatted := beam.ParDo(s, formatFn, counted[0])
+ textio.Write(s, *output, formatted)
+
+ // Concept #1: The beamx.Run convenience wrapper allows a number of
Review comment:
Ack.
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