John Naylor <[email protected]> writes:
> On Tue, Jan 8, 2019 at 12:06 PM Andrew Dunstan
> <[email protected]> wrote:
>> If he doesn't I will.
> I'll take a crack at separating into a module. I'll wait a bit in
> case there are any stylistic suggestions on the patch as it stands.
I had a go at that myself. I'm sure there's plenty to criticize in
the result, but at least it passes make check-world ;-)
I resolved the worry I had last night about the range of table values
by putting in logic to check the range and choose a suitable table
element type. There are a couple of existing calls where we manage
to fit the hashtable elements into int8 that way; of course, by
definition that doesn't save a whole lot of space since such tables
couldn't have many elements, but it seems cleaner anyway.
regards, tom lane
diff --git a/src/common/Makefile b/src/common/Makefile
index 317b071..d0c2b97 100644
*** a/src/common/Makefile
--- b/src/common/Makefile
*************** OBJS_FRONTEND = $(OBJS_COMMON) fe_memuti
*** 63,68 ****
--- 63,73 ----
OBJS_SHLIB = $(OBJS_FRONTEND:%.o=%_shlib.o)
OBJS_SRV = $(OBJS_COMMON:%.o=%_srv.o)
+ # where to find gen_keywordlist.pl and subsidiary files
+ TOOLSDIR = $(top_srcdir)/src/tools
+ GEN_KEYWORDLIST = $(PERL) -I $(TOOLSDIR) $(TOOLSDIR)/gen_keywordlist.pl
+ GEN_KEYWORDLIST_DEPS = $(TOOLSDIR)/gen_keywordlist.pl $(TOOLSDIR)/PerfectHash.pm
+
all: libpgcommon.a libpgcommon_shlib.a libpgcommon_srv.a
distprep: kwlist_d.h
*************** libpgcommon_srv.a: $(OBJS_SRV)
*** 118,125 ****
$(CC) $(CFLAGS) $(subst -DFRONTEND,, $(CPPFLAGS)) -c $< -o $@
# generate SQL keyword lookup table to be included into keywords*.o.
! kwlist_d.h: $(top_srcdir)/src/include/parser/kwlist.h $(top_srcdir)/src/tools/gen_keywordlist.pl
! $(PERL) $(top_srcdir)/src/tools/gen_keywordlist.pl --extern $<
# Dependencies of keywords*.o need to be managed explicitly to make sure
# that you don't get broken parsing code, even in a non-enable-depend build.
--- 123,130 ----
$(CC) $(CFLAGS) $(subst -DFRONTEND,, $(CPPFLAGS)) -c $< -o $@
# generate SQL keyword lookup table to be included into keywords*.o.
! kwlist_d.h: $(top_srcdir)/src/include/parser/kwlist.h $(GEN_KEYWORDLIST_DEPS)
! $(GEN_KEYWORDLIST) --extern $<
# Dependencies of keywords*.o need to be managed explicitly to make sure
# that you don't get broken parsing code, even in a non-enable-depend build.
diff --git a/src/common/kwlookup.c b/src/common/kwlookup.c
index d72842e..9dc1fee 100644
*** a/src/common/kwlookup.c
--- b/src/common/kwlookup.c
***************
*** 35,94 ****
* receive a different case-normalization mapping.
*/
int
! ScanKeywordLookup(const char *text,
const ScanKeywordList *keywords)
{
! int len,
! i;
! char word[NAMEDATALEN];
! const char *kw_string;
! const uint16 *kw_offsets;
! const uint16 *low;
! const uint16 *high;
!
! len = strlen(text);
if (len > keywords->max_kw_len)
! return -1; /* too long to be any keyword */
!
! /* We assume all keywords are shorter than NAMEDATALEN. */
! Assert(len < NAMEDATALEN);
/*
! * Apply an ASCII-only downcasing. We must not use tolower() since it may
! * produce the wrong translation in some locales (eg, Turkish).
*/
! for (i = 0; i < len; i++)
! {
! char ch = text[i];
! if (ch >= 'A' && ch <= 'Z')
! ch += 'a' - 'A';
! word[i] = ch;
! }
! word[len] = '\0';
/*
! * Now do a binary search using plain strcmp() comparison.
*/
! kw_string = keywords->kw_string;
! kw_offsets = keywords->kw_offsets;
! low = kw_offsets;
! high = kw_offsets + (keywords->num_keywords - 1);
! while (low <= high)
{
! const uint16 *middle;
! int difference;
! middle = low + (high - low) / 2;
! difference = strcmp(kw_string + *middle, word);
! if (difference == 0)
! return middle - kw_offsets;
! else if (difference < 0)
! low = middle + 1;
! else
! high = middle - 1;
}
! return -1;
}
--- 35,89 ----
* receive a different case-normalization mapping.
*/
int
! ScanKeywordLookup(const char *str,
const ScanKeywordList *keywords)
{
! size_t len;
! int h;
! const char *kw;
+ /*
+ * Reject immediately if too long to be any keyword. This saves useless
+ * hashing and downcasing work on long strings.
+ */
+ len = strlen(str);
if (len > keywords->max_kw_len)
! return -1;
/*
! * Compute the hash function. We assume it was generated to produce
! * case-insensitive results. Since it's a perfect hash, we need only
! * match to the specific keyword it identifies.
*/
! h = keywords->hash(str, len);
! /*
! * An out-of-range result implies no match. (This can happen for
! * non-keyword inputs because the hash function will sum two unrelated
! * hashtable entries.)
! */
! if (h < 0 || h >= keywords->num_keywords)
! return -1;
/*
! * Compare character-by-character to see if we have a match, applying an
! * ASCII-only downcasing to the input characters. We must not use
! * tolower() since it may produce the wrong translation in some locales
! * (eg, Turkish).
*/
! kw = GetScanKeyword(h, keywords);
! while (*str != '\0')
{
! char ch = *str++;
! if (ch >= 'A' && ch <= 'Z')
! ch += 'a' - 'A';
! if (ch != *kw++)
! return -1;
}
+ if (*kw != '\0')
+ return -1;
! /* Success! */
! return h;
}
diff --git a/src/include/common/kwlookup.h b/src/include/common/kwlookup.h
index 39efb35..dbff367 100644
*** a/src/include/common/kwlookup.h
--- b/src/include/common/kwlookup.h
***************
*** 14,19 ****
--- 14,22 ----
#ifndef KWLOOKUP_H
#define KWLOOKUP_H
+ /* Hash function used by ScanKeywordLookup */
+ typedef int (*ScanKeywordHashFunc) (const void *key, size_t keylen);
+
/*
* This struct contains the data needed by ScanKeywordLookup to perform a
* search within a set of keywords. The contents are typically generated by
*************** typedef struct ScanKeywordList
*** 23,28 ****
--- 26,32 ----
{
const char *kw_string; /* all keywords in order, separated by \0 */
const uint16 *kw_offsets; /* offsets to the start of each keyword */
+ ScanKeywordHashFunc hash; /* perfect hash function for keywords */
int num_keywords; /* number of keywords */
int max_kw_len; /* length of longest keyword */
} ScanKeywordList;
diff --git a/src/interfaces/ecpg/preproc/Makefile b/src/interfaces/ecpg/preproc/Makefile
index b5b74a3..6c02f97 100644
*** a/src/interfaces/ecpg/preproc/Makefile
--- b/src/interfaces/ecpg/preproc/Makefile
*************** OBJS= preproc.o pgc.o type.o ecpg.o outp
*** 28,34 ****
keywords.o c_keywords.o ecpg_keywords.o typename.o descriptor.o variable.o \
$(WIN32RES)
! GEN_KEYWORDLIST = $(top_srcdir)/src/tools/gen_keywordlist.pl
# Suppress parallel build to avoid a bug in GNU make 3.82
# (see comments in ../Makefile)
--- 28,37 ----
keywords.o c_keywords.o ecpg_keywords.o typename.o descriptor.o variable.o \
$(WIN32RES)
! # where to find gen_keywordlist.pl and subsidiary files
! TOOLSDIR = $(top_srcdir)/src/tools
! GEN_KEYWORDLIST = $(PERL) -I $(TOOLSDIR) $(TOOLSDIR)/gen_keywordlist.pl
! GEN_KEYWORDLIST_DEPS = $(TOOLSDIR)/gen_keywordlist.pl $(TOOLSDIR)/PerfectHash.pm
# Suppress parallel build to avoid a bug in GNU make 3.82
# (see comments in ../Makefile)
*************** preproc.y: ../../../backend/parser/gram.
*** 56,66 ****
$(PERL) $(srcdir)/check_rules.pl $(srcdir) $<
# generate keyword headers
! c_kwlist_d.h: c_kwlist.h $(GEN_KEYWORDLIST)
! $(PERL) $(GEN_KEYWORDLIST) --varname ScanCKeywords $<
! ecpg_kwlist_d.h: ecpg_kwlist.h $(GEN_KEYWORDLIST)
! $(PERL) $(GEN_KEYWORDLIST) --varname ScanECPGKeywords $<
# Force these dependencies to be known even without dependency info built:
ecpg_keywords.o c_keywords.o keywords.o preproc.o pgc.o parser.o: preproc.h
--- 59,69 ----
$(PERL) $(srcdir)/check_rules.pl $(srcdir) $<
# generate keyword headers
! c_kwlist_d.h: c_kwlist.h $(GEN_KEYWORDLIST_DEPS)
! $(GEN_KEYWORDLIST) --varname ScanCKeywords --case $<
! ecpg_kwlist_d.h: ecpg_kwlist.h $(GEN_KEYWORDLIST_DEPS)
! $(GEN_KEYWORDLIST) --varname ScanECPGKeywords $<
# Force these dependencies to be known even without dependency info built:
ecpg_keywords.o c_keywords.o keywords.o preproc.o pgc.o parser.o: preproc.h
diff --git a/src/interfaces/ecpg/preproc/c_keywords.c b/src/interfaces/ecpg/preproc/c_keywords.c
index 38ddf6f..387298b 100644
*** a/src/interfaces/ecpg/preproc/c_keywords.c
--- b/src/interfaces/ecpg/preproc/c_keywords.c
***************
*** 9,16 ****
*/
#include "postgres_fe.h"
- #include <ctype.h>
-
#include "preproc_extern.h"
#include "preproc.h"
--- 9,14 ----
*************** static const uint16 ScanCKeywordTokens[]
*** 32,70 ****
*
* Returns the token value of the keyword, or -1 if no match.
*
! * Do a binary search using plain strcmp() comparison. This is much like
* ScanKeywordLookup(), except we want case-sensitive matching.
*/
int
! ScanCKeywordLookup(const char *text)
{
! const char *kw_string;
! const uint16 *kw_offsets;
! const uint16 *low;
! const uint16 *high;
! if (strlen(text) > ScanCKeywords.max_kw_len)
! return -1; /* too long to be any keyword */
! kw_string = ScanCKeywords.kw_string;
! kw_offsets = ScanCKeywords.kw_offsets;
! low = kw_offsets;
! high = kw_offsets + (ScanCKeywords.num_keywords - 1);
! while (low <= high)
! {
! const uint16 *middle;
! int difference;
! middle = low + (high - low) / 2;
! difference = strcmp(kw_string + *middle, text);
! if (difference == 0)
! return ScanCKeywordTokens[middle - kw_offsets];
! else if (difference < 0)
! low = middle + 1;
! else
! high = middle - 1;
! }
return -1;
}
--- 30,71 ----
*
* Returns the token value of the keyword, or -1 if no match.
*
! * Do a hash search using plain strcmp() comparison. This is much like
* ScanKeywordLookup(), except we want case-sensitive matching.
*/
int
! ScanCKeywordLookup(const char *str)
{
! size_t len;
! int h;
! const char *kw;
! /*
! * Reject immediately if too long to be any keyword. This saves useless
! * hashing work on long strings.
! */
! len = strlen(str);
! if (len > ScanCKeywords.max_kw_len)
! return -1;
! /*
! * Compute the hash function. Since it's a perfect hash, we need only
! * match to the specific keyword it identifies.
! */
! h = ScanCKeywords_hash_func(str, len);
! /*
! * An out-of-range result implies no match. (This can happen for
! * non-keyword inputs because the hash function will sum two unrelated
! * hashtable entries.)
! */
! if (h < 0 || h >= ScanCKeywords.num_keywords)
! return -1;
! kw = GetScanKeyword(h, &ScanCKeywords);
!
! if (strcmp(kw, str) == 0)
! return ScanCKeywordTokens[h];
return -1;
}
diff --git a/src/pl/plpgsql/src/Makefile b/src/pl/plpgsql/src/Makefile
index 9dd4a74..8a0f294 100644
*** a/src/pl/plpgsql/src/Makefile
--- b/src/pl/plpgsql/src/Makefile
*************** REGRESS_OPTS = --dbname=$(PL_TESTDB)
*** 29,35 ****
REGRESS = plpgsql_call plpgsql_control plpgsql_domain plpgsql_record \
plpgsql_cache plpgsql_transaction plpgsql_varprops
! GEN_KEYWORDLIST = $(top_srcdir)/src/tools/gen_keywordlist.pl
all: all-lib
--- 29,38 ----
REGRESS = plpgsql_call plpgsql_control plpgsql_domain plpgsql_record \
plpgsql_cache plpgsql_transaction plpgsql_varprops
! # where to find gen_keywordlist.pl and subsidiary files
! TOOLSDIR = $(top_srcdir)/src/tools
! GEN_KEYWORDLIST = $(PERL) -I $(TOOLSDIR) $(TOOLSDIR)/gen_keywordlist.pl
! GEN_KEYWORDLIST_DEPS = $(TOOLSDIR)/gen_keywordlist.pl $(TOOLSDIR)/PerfectHash.pm
all: all-lib
*************** plerrcodes.h: $(top_srcdir)/src/backend/
*** 76,86 ****
$(PERL) $(srcdir)/generate-plerrcodes.pl $< > $@
# generate keyword headers for the scanner
! pl_reserved_kwlist_d.h: pl_reserved_kwlist.h $(GEN_KEYWORDLIST)
! $(PERL) $(GEN_KEYWORDLIST) --varname ReservedPLKeywords $<
! pl_unreserved_kwlist_d.h: pl_unreserved_kwlist.h $(GEN_KEYWORDLIST)
! $(PERL) $(GEN_KEYWORDLIST) --varname UnreservedPLKeywords $<
check: submake
--- 79,89 ----
$(PERL) $(srcdir)/generate-plerrcodes.pl $< > $@
# generate keyword headers for the scanner
! pl_reserved_kwlist_d.h: pl_reserved_kwlist.h $(GEN_KEYWORDLIST_DEPS)
! $(GEN_KEYWORDLIST) --varname ReservedPLKeywords $<
! pl_unreserved_kwlist_d.h: pl_unreserved_kwlist.h $(GEN_KEYWORDLIST_DEPS)
! $(GEN_KEYWORDLIST) --varname UnreservedPLKeywords $<
check: submake
diff --git a/src/tools/PerfectHash.pm b/src/tools/PerfectHash.pm
index ...34d55cf .
*** a/src/tools/PerfectHash.pm
--- b/src/tools/PerfectHash.pm
***************
*** 0 ****
--- 1,336 ----
+ #----------------------------------------------------------------------
+ #
+ # PerfectHash.pm
+ # Perl module that constructs minimal perfect hash functions
+ #
+ # This code constructs a minimal perfect hash function for the given
+ # set of keys, using an algorithm described in
+ # "An optimal algorithm for generating minimal perfect hash functions"
+ # by Czech, Havas and Majewski in Information Processing Letters,
+ # 43(5):256-264, October 1992.
+ # This implementation is loosely based on NetBSD's "nbperf",
+ # which was written by Joerg Sonnenberger.
+ #
+ # The resulting hash function is perfect in the sense that if the presented
+ # key is one of the original set, it will return the key's index in the set
+ # (in range 0..N-1). However, the caller must still verify the match,
+ # as false positives are possible. Also, the hash function may return
+ # values that are out of range (negative, or >= N). This indicates that
+ # the presented key is definitely not in the set.
+ #
+ #
+ # Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
+ # Portions Copyright (c) 1994, Regents of the University of California
+ #
+ # src/tools/PerfectHash.pm
+ #
+ #----------------------------------------------------------------------
+
+ package PerfectHash;
+
+ use strict;
+ use warnings;
+ use Exporter 'import';
+
+ our @EXPORT_OK = qw(
+ generate_hash_function
+ );
+
+
+ # At runtime, we'll compute two simple hash functions of the input key,
+ # and use them to index into a mapping table. The hash functions are just
+ # multiply-and-add in uint32 arithmetic, with different multipliers but
+ # the same initial seed. All the complexity in this module is concerned
+ # with selecting hash parameters that will work and building the mapping
+ # table.
+
+ # We support making case-insensitive hash functions, though this only
+ # works for a strict-ASCII interpretation of case insensitivity,
+ # ie, A-Z maps onto a-z and nothing else.
+ my $case_insensitive = 0;
+
+
+ #
+ # Construct a C function implementing a perfect hash for the given keys.
+ # The C function definition is returned as a string.
+ #
+ # The keys can be any set of Perl strings; it is caller's responsibility
+ # that there not be any duplicates. (Note that the "strings" can be
+ # binary data, but endianness is the caller's problem.)
+ #
+ # The name to use for the function is caller-specified, but its signature
+ # is always "int f(const void *key, size_t keylen)". The caller may
+ # prepend "static " to the result string if it wants a static function.
+ #
+ # If $ci is true, the function is case-insensitive, for the limited idea
+ # of case-insensitivity explained above.
+ #
+ sub generate_hash_function
+ {
+ my ($keys_ref, $funcname, $ci) = @_;
+
+ # It's not worth passing this around as a parameter; just use a global.
+ $case_insensitive = $ci;
+
+ # Try different hash function parameters until we find a set that works
+ # for these keys. In principle we might need to change multipliers,
+ # but these two multipliers are chosen to be cheap to calculate via
+ # shift-and-add, so don't change them except at great need.
+ my $hash_mult1 = 31;
+ my $hash_mult2 = 37;
+
+ # We just try successive hash seed values until we find one that works.
+ # (Commonly, random seeds are tried, but we want reproducible results
+ # from this program so we don't do that.)
+ my $hash_seed;
+ my @subresult;
+ for ($hash_seed = 0;; $hash_seed++)
+ {
+ @subresult =
+ _construct_hash_table($keys_ref, $hash_mult1, $hash_mult2,
+ $hash_seed);
+ last if @subresult;
+ }
+
+ # Extract info from the function result array.
+ my $elemtype = $subresult[0];
+ my @hashtab = @{ $subresult[1] };
+ my $nhash = scalar(@hashtab);
+
+ # OK, construct the hash function definition including the hash table.
+ my $f = '';
+ $f .= sprintf "int\n";
+ $f .= sprintf "%s(const void *key, size_t keylen)\n{\n", $funcname;
+ $f .= sprintf "\tstatic const %s h[%d] = {\n", $elemtype, $nhash;
+ for (my $i = 0; $i < $nhash; $i++)
+ {
+ $f .= sprintf "%s%6d,%s",
+ ($i % 8 == 0 ? "\t\t" : " "),
+ $hashtab[$i],
+ ($i % 8 == 7 ? "\n" : "");
+ }
+ $f .= sprintf "\n" if ($nhash % 8 != 0);
+ $f .= sprintf "\t};\n\n";
+ $f .= sprintf "\tconst unsigned char *k = key;\n";
+ $f .= sprintf "\tuint32\t\ta = %d;\n", $hash_seed;
+ $f .= sprintf "\tuint32\t\tb = %d;\n\n", $hash_seed;
+ $f .= sprintf "\twhile (keylen--)\n\t{\n";
+ $f .= sprintf "\t\tunsigned char c = *k++";
+ $f .= sprintf " | 0x20" if $case_insensitive; # see comment below
+ $f .= sprintf ";\n\n";
+ $f .= sprintf "\t\ta = a * %d + c;\n", $hash_mult1;
+ $f .= sprintf "\t\tb = b * %d + c;\n", $hash_mult2;
+ $f .= sprintf "\t}\n";
+ $f .= sprintf "\treturn h[a %% %d] + h[b %% %d];\n", $nhash, $nhash;
+ $f .= sprintf "}\n";
+
+ return $f;
+ }
+
+
+ # Calculate a hash function as the run-time code will do.
+ #
+ # If we are making a case-insensitive hash function, we implement that
+ # by OR'ing 0x20 into each byte of the key. This correctly transforms
+ # upper-case ASCII into lower-case ASCII, while not changing digits or
+ # dollar signs. (It does change '_', else we could just skip adjusting
+ # $cn here at all, for typical keyword strings.)
+ sub _calc_hash
+ {
+ my ($key, $mult, $seed) = @_;
+
+ my $result = $seed;
+ for my $c (split //, $key)
+ {
+ my $cn = ord($c);
+ $cn |= 0x20 if $case_insensitive;
+ $result = ($result * $mult + $cn) % 4294967296;
+ }
+ return $result;
+ }
+
+
+ # Attempt to construct a mapping table for a minimal perfect hash function
+ # for the given keys, using the specified hash parameters.
+ #
+ # Returns an array containing the mapping table element type name as the
+ # first element, and a ref to an array of the table values as the second.
+ #
+ # Returns an empty array on failure; then caller should choose different
+ # hash parameter(s) and try again.
+ sub _construct_hash_table
+ {
+ my ($keys_ref, $hash_mult1, $hash_mult2, $hash_seed) = @_;
+ my @keys = @{$keys_ref};
+
+ # This algorithm is based on a graph whose edges correspond to the
+ # keys and whose vertices correspond to entries of the mapping table.
+ # A key edge links the two vertices whose indexes are the outputs of
+ # the two hash functions for that key. For K keys, the mapping
+ # table must have at least 2*K+1 entries, guaranteeing that there's at
+ # least one unused entry. (In principle, larger mapping tables make it
+ # easier to find a workable hash and increase the number of inputs that
+ # can be rejected due to touching unused hashtable entries. In practice,
+ # neither effect seems strong enough to justify using a larger table.)
+ my $nedges = scalar @keys; # number of edges
+ my $nverts = 2 * $nedges + 1; # number of vertices
+
+ # Initialize the array of edges.
+ my @E = ();
+ foreach my $kw (@keys)
+ {
+ # Calculate hashes for this key.
+ # The hashes are immediately reduced modulo the mapping table size.
+ my $hash1 = _calc_hash($kw, $hash_mult1, $hash_seed) % $nverts;
+ my $hash2 = _calc_hash($kw, $hash_mult2, $hash_seed) % $nverts;
+
+ # If the two hashes are the same for any key, we have to fail
+ # since this edge would itself form a cycle in the graph.
+ return () if $hash1 == $hash2;
+
+ # Add the edge for this key.
+ push @E, { left => $hash1, right => $hash2 };
+ }
+
+ # Initialize the array of vertices, giving them all empty lists
+ # of associated edges. (The lists will be hashes of edge numbers.)
+ my @V = ();
+ for (my $v = 0; $v < $nverts; $v++)
+ {
+ push @V, { edges => {} };
+ }
+
+ # Insert each edge in the lists of edges using its vertices.
+ for (my $e = 0; $e < $nedges; $e++)
+ {
+ my $v = $E[$e]{left};
+ $V[$v]{edges}->{$e} = 1;
+
+ $v = $E[$e]{right};
+ $V[$v]{edges}->{$e} = 1;
+ }
+
+ # Now we attempt to prove the graph acyclic.
+ # A cycle-free graph is either empty or has some vertex of degree 1.
+ # Removing the edge attached to that vertex doesn't change this property,
+ # so doing that repeatedly will reduce the size of the graph.
+ # If the graph is empty at the end of the process, it was acyclic.
+ # We track the order of edge removal so that the next phase can process
+ # them in reverse order of removal.
+ my @output_order = ();
+
+ # Consider each vertex as a possible starting point for edge-removal.
+ for (my $startv = 0; $startv < $nverts; $startv++)
+ {
+ my $v = $startv;
+
+ # If vertex v is of degree 1 (i.e. exactly 1 edge connects to it),
+ # remove that edge, and then consider the edge's other vertex to see
+ # if it is now of degree 1. The inner loop repeats until reaching a
+ # vertex not of degree 1.
+ while (scalar(keys(%{ $V[$v]{edges} })) == 1)
+ {
+ # Unlink its only edge.
+ my $e = (keys(%{ $V[$v]{edges} }))[0];
+ delete($V[$v]{edges}->{$e});
+
+ # Unlink the edge from its other vertex, too.
+ my $v2 = $E[$e]{left};
+ $v2 = $E[$e]{right} if ($v2 == $v);
+ delete($V[$v2]{edges}->{$e});
+
+ # Push e onto the front of the output-order list.
+ unshift @output_order, $e;
+
+ # Consider v2 on next iteration of inner loop.
+ $v = $v2;
+ }
+ }
+
+ # We succeeded only if all edges were removed from the graph.
+ return () if (scalar(@output_order) != $nedges);
+
+ # OK, build the hash table of size $nverts.
+ my @hashtab = (0) x $nverts;
+ # We need a "visited" flag array in this step, too.
+ my @visited = (0) x $nverts;
+
+ # The idea is that for any key, the sum of the hash table entries
+ # for its first and second hash values is the desired output (i.e., the
+ # key number). By assigning hash table values in the selected edge
+ # order, we can guarantee that that's true.
+ foreach my $e (@output_order)
+ {
+ my $l = $E[$e]{left};
+ my $r = $E[$e]{right};
+ if (!$visited[$l])
+ {
+ # $hashtab[$r] might be zero, or some previously assigned value.
+ $hashtab[$l] = $e - $hashtab[$r];
+ }
+ else
+ {
+ die "oops, doubly used hashtab entry" if $visited[$r];
+ # $hashtab[$l] might be zero, or some previously assigned value.
+ $hashtab[$r] = $e - $hashtab[$l];
+ }
+ # Now freeze both of these hashtab entries.
+ $visited[$l] = 1;
+ $visited[$r] = 1;
+ }
+
+ # Detect range of values needed in hash table.
+ my $hmin = $nedges;
+ my $hmax = 0;
+ for (my $v = 0; $v < $nverts; $v++)
+ {
+ $hmin = $hashtab[$v] if $hashtab[$v] < $hmin;
+ $hmax = $hashtab[$v] if $hashtab[$v] > $hmax;
+ }
+
+ # Choose width of hashtable entries. In addition to the actual values,
+ # we need to be able to store a flag for unused entries, and we wish to
+ # have the property that adding any other entry value to the flag gives
+ # an out-of-range result (>= $nedges).
+ my $elemtype;
+ my $unused_flag;
+
+ if ( $hmin >= -0x7F
+ && $hmax <= 0x7F
+ && $hmin + 0x7F >= $nedges)
+ {
+ # int8 will work
+ $elemtype = 'int8';
+ $unused_flag = 0x7F;
+ }
+ elsif ($hmin >= -0x7FFF
+ && $hmax <= 0x7FFF
+ && $hmin + 0x7FFF >= $nedges)
+ {
+ # int16 will work
+ $elemtype = 'int16';
+ $unused_flag = 0x7FFF;
+ }
+ elsif ($hmin >= -0x7FFFFFFF
+ && $hmax <= 0x7FFFFFFF
+ && $hmin + 0x3FFFFFFF >= $nedges)
+ {
+ # int32 will work
+ $elemtype = 'int32';
+ $unused_flag = 0x3FFFFFFF;
+ }
+ else
+ {
+ die "hash table values too wide";
+ }
+
+ # Set any unvisited hashtable entries to $unused_flag.
+ for (my $v = 0; $v < $nverts; $v++)
+ {
+ $hashtab[$v] = $unused_flag if !$visited[$v];
+ }
+
+ return ($elemtype, \@hashtab);
+ }
+
+ 1;
diff --git a/src/tools/gen_keywordlist.pl b/src/tools/gen_keywordlist.pl
index d764aff..e912c3e 100644
*** a/src/tools/gen_keywordlist.pl
--- b/src/tools/gen_keywordlist.pl
***************
*** 14,19 ****
--- 14,25 ----
# variable named according to the -v switch ("ScanKeywords" by default).
# The variable is marked "static" unless the -e switch is given.
#
+ # ScanKeywordList uses hash-based lookup, so this script also selects
+ # a minimal perfect hash function for the keyword set, and emits a
+ # static hash function that is referenced in the ScanKeywordList struct.
+ # The hash function is case-insensitive unless --case is specified.
+ # Note that case insensitivity assumes all-ASCII keywords!
+ #
#
# Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
# Portions Copyright (c) 1994, Regents of the University of California
***************
*** 25,39 ****
use strict;
use warnings;
use Getopt::Long;
my $output_path = '';
my $extern = 0;
my $varname = 'ScanKeywords';
GetOptions(
! 'output:s' => \$output_path,
! 'extern' => \$extern,
! 'varname:s' => \$varname) || usage();
my $kw_input_file = shift @ARGV || die "No input file.\n";
--- 31,48 ----
use strict;
use warnings;
use Getopt::Long;
+ use PerfectHash;
my $output_path = '';
my $extern = 0;
+ my $case_sensitive = 0;
my $varname = 'ScanKeywords';
GetOptions(
! 'output:s' => \$output_path,
! 'extern' => \$extern,
! 'case-sensitive' => \$case_sensitive,
! 'varname:s' => \$varname) || usage();
my $kw_input_file = shift @ARGV || die "No input file.\n";
*************** while (<$kif>)
*** 87,93 ****
--- 96,117 ----
}
}
+ # When being case-insensitive, insist that the input be all-lower-case.
+ if (!$case_sensitive)
+ {
+ foreach my $kw (@keywords)
+ {
+ die qq|The keyword "$kw" is not lower-case in $kw_input_file\n|
+ if ($kw ne lc $kw);
+ }
+ }
+
# Error out if the keyword names are not in ASCII order.
+ #
+ # While this isn't really necessary with hash-based lookup, it's still
+ # helpful because it provides a cheap way to reject duplicate keywords.
+ # Also, insisting on sorted order ensures that code that scans the keyword
+ # table linearly will see the keywords in a canonical order.
for my $i (0..$#keywords - 1)
{
die qq|The keyword "$keywords[$i + 1]" is out of order in $kw_input_file\n|
*************** print $kwdef "};\n\n";
*** 128,142 ****
printf $kwdef "#define %s_NUM_KEYWORDS %d\n\n", uc $varname, scalar @keywords;
# Emit the struct that wraps all this lookup info into one variable.
! print $kwdef "static " if !$extern;
printf $kwdef "const ScanKeywordList %s = {\n", $varname;
printf $kwdef qq|\t%s_kw_string,\n|, $varname;
printf $kwdef qq|\t%s_kw_offsets,\n|, $varname;
printf $kwdef qq|\t%s_NUM_KEYWORDS,\n|, uc $varname;
printf $kwdef qq|\t%d\n|, $max_len;
! print $kwdef "};\n\n";
printf $kwdef "#endif\t\t\t\t\t\t\t/* %s_H */\n", uc $base_filename;
--- 152,176 ----
printf $kwdef "#define %s_NUM_KEYWORDS %d\n\n", uc $varname, scalar @keywords;
+ # Emit the definition of the hash function.
+
+ my $funcname = $varname . "_hash_func";
+
+ my $f = PerfectHash::generate_hash_function(\@keywords,
+ $funcname, !$case_sensitive);
+
+ printf $kwdef qq|static %s\n|, $f;
+
# Emit the struct that wraps all this lookup info into one variable.
! printf $kwdef "static " if !$extern;
printf $kwdef "const ScanKeywordList %s = {\n", $varname;
printf $kwdef qq|\t%s_kw_string,\n|, $varname;
printf $kwdef qq|\t%s_kw_offsets,\n|, $varname;
+ printf $kwdef qq|\t%s,\n|, $funcname;
printf $kwdef qq|\t%s_NUM_KEYWORDS,\n|, uc $varname;
printf $kwdef qq|\t%d\n|, $max_len;
! printf $kwdef "};\n\n";
printf $kwdef "#endif\t\t\t\t\t\t\t/* %s_H */\n", uc $base_filename;
*************** Usage: gen_keywordlist.pl [--output/-o <
*** 148,153 ****
--- 182,188 ----
--output Output directory (default '.')
--varname Name for ScanKeywordList variable (default 'ScanKeywords')
--extern Allow the ScanKeywordList variable to be globally visible
+ --case Keyword matching is to be case-sensitive
gen_keywordlist.pl transforms a list of keywords into a ScanKeywordList.
The output filename is derived from the input file by inserting _d,
diff --git a/src/tools/msvc/Solution.pm b/src/tools/msvc/Solution.pm
index 937bf18..8f54e45 100644
*** a/src/tools/msvc/Solution.pm
--- b/src/tools/msvc/Solution.pm
*************** sub GenerateFiles
*** 414,420 ****
'src/include/parser/kwlist.h'))
{
print "Generating kwlist_d.h...\n";
! system('perl src/tools/gen_keywordlist.pl --extern -o src/common src/include/parser/kwlist.h');
}
if (IsNewer(
--- 414,420 ----
'src/include/parser/kwlist.h'))
{
print "Generating kwlist_d.h...\n";
! system('perl -I src/tools src/tools/gen_keywordlist.pl --extern -o src/common src/include/parser/kwlist.h');
}
if (IsNewer(
*************** sub GenerateFiles
*** 426,433 ****
{
print "Generating pl_reserved_kwlist_d.h and pl_unreserved_kwlist_d.h...\n";
chdir('src/pl/plpgsql/src');
! system('perl ../../../tools/gen_keywordlist.pl --varname ReservedPLKeywords pl_reserved_kwlist.h');
! system('perl ../../../tools/gen_keywordlist.pl --varname UnreservedPLKeywords pl_unreserved_kwlist.h');
chdir('../../../..');
}
--- 426,433 ----
{
print "Generating pl_reserved_kwlist_d.h and pl_unreserved_kwlist_d.h...\n";
chdir('src/pl/plpgsql/src');
! system('perl -I ../../../tools ../../../tools/gen_keywordlist.pl --varname ReservedPLKeywords pl_reserved_kwlist.h');
! system('perl -I ../../../tools ../../../tools/gen_keywordlist.pl --varname UnreservedPLKeywords pl_unreserved_kwlist.h');
chdir('../../../..');
}
*************** sub GenerateFiles
*** 440,447 ****
{
print "Generating c_kwlist_d.h and ecpg_kwlist_d.h...\n";
chdir('src/interfaces/ecpg/preproc');
! system('perl ../../../tools/gen_keywordlist.pl --varname ScanCKeywords c_kwlist.h');
! system('perl ../../../tools/gen_keywordlist.pl --varname ScanECPGKeywords ecpg_kwlist.h');
chdir('../../../..');
}
--- 440,447 ----
{
print "Generating c_kwlist_d.h and ecpg_kwlist_d.h...\n";
chdir('src/interfaces/ecpg/preproc');
! system('perl -I ../../../tools ../../../tools/gen_keywordlist.pl --varname ScanCKeywords --case c_kwlist.h');
! system('perl -I ../../../tools ../../../tools/gen_keywordlist.pl --varname ScanECPGKeywords ecpg_kwlist.h');
chdir('../../../..');
}
