Add sample text search dictionary templates and parsers, to replace the

hard-to-maintain textual examples currently in the SGML docs.  From
Sergey Karpov.

contrib/dict_xsyn/Makefile

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+# $PostgreSQL: pgsql/contrib/dict_xsyn/Makefile,v 1.1 2007/10/15 21:36:50 tgl Exp $
+
+MODULE_big = dict_xsyn
+OBJS = dict_xsyn.o
+DATA_built = dict_xsyn.sql
+DATA = uninstall_dict_xsyn.sql
+DOCS = README.dict_xsyn
+REGRESS = dict_xsyn
+
+DICTDIR = tsearch_data
+DICTFILES = xsyn_sample.rules
+
+ifdef USE_PGXS
+PG_CONFIG = pg_config
+PGXS := $(shell $(PG_CONFIG) --pgxs)
+include $(PGXS)
+else
+subdir = contrib/dict_xsyn
+top_builddir = ../..
+include $(top_builddir)/src/Makefile.global
+include $(top_srcdir)/contrib/contrib-global.mk
+endif
+
+install: install-data
+
+.PHONY: install-data
+install-data: $(DICTFILES)
+	for i in $(DICTFILES); \
+		do $(INSTALL_DATA) $(srcdir)/$$i '$(DESTDIR)$(datadir)/$(DICTDIR)/'$$i; \
+	done
+
+uninstall: uninstall-data
+
+.PHONY: uninstall-data
+uninstall-data:
+	for i in $(DICTFILES); \
+		do rm -rf '$(DESTDIR)$(datadir)/$(DICTDIR)/'$$i ; \
+	done

contrib/dict_xsyn/README.dict_xsyn

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+Extended Synonym dictionary
+===========================
+
+This is a simple synonym dictionary. It replaces words with groups of their
+synonyms, and so makes it possible to search for a word using any of its
+synonyms.
+
+* Configuration
+
+It accepts the following options:
+ 
+ - KEEPORIG controls whether the original word is included, or only its
+   synonyms. Default is 'true'.
+
+ - RULES is the base name of the file containing the list of synonyms.
+   This file must be in $(prefix)/share/tsearch_data/, and its name must
+   end in ".rules" (which is not included in the RULES parameter).
+
+The rules file has the following format:
+
+ - Each line represents a group of synonyms for a single word, which is
+   given first on the line. Synonyms are separated by whitespace:
+   
+   word syn1 syn2 syn3
+
+ - Sharp ('#') sign is a comment delimiter. It may appear at any position
+   inside the line.  The rest of the line will be skipped.
+
+Look at xsyn_sample.rules, which is installed in $(prefix)/share/tsearch_data/,
+for an example.
+
+* Usage
+
+1. Compile and install
+
+2. Load dictionary
+
+   psql mydb < dict_xsyn.sql
+
+3. Test it
+ 
+   mydb=# SELECT ts_lexize('xsyn','word');
+   ts_lexize
+   ----------------
+   {word,syn1,syn2,syn3)
+
+4. Change the dictionary options as you wish
+
+   mydb# ALTER TEXT SEARCH DICTIONARY xsyn (KEEPORIG=false);
+   ALTER TEXT SEARCH DICTIONARY
+
+That's all.

contrib/dict_xsyn/dict_xsyn.c

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+/*-------------------------------------------------------------------------
+ *
+ * dict_xsyn.c
+ *	  Extended synonym dictionary
+ *
+ * Copyright (c) 2007, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  $PostgreSQL: pgsql/contrib/dict_xsyn/dict_xsyn.c,v 1.1 2007/10/15 21:36:50 tgl Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include <ctype.h>
+
+#include "commands/defrem.h"
+#include "fmgr.h"
+#include "storage/fd.h"
+#include "tsearch/ts_locale.h"
+#include "tsearch/ts_utils.h"
+
+PG_MODULE_MAGIC;
+
+typedef struct
+{
+	char *key; /* Word */
+	char *value; /* Unparsed list of synonyms, including the word itself */
+}	Syn;
+
+typedef struct
+{
+	int len;
+	Syn *syn;
+
+	bool keeporig;
+}	DictSyn;
+
+
+PG_FUNCTION_INFO_V1(dxsyn_init);
+Datum dxsyn_init(PG_FUNCTION_ARGS);
+
+PG_FUNCTION_INFO_V1(dxsyn_lexize);
+Datum dxsyn_lexize(PG_FUNCTION_ARGS);
+
+static char *
+find_word(char *in, char **end)
+{
+	char *start;
+
+	*end = NULL;
+	while (*in && t_isspace(in))
+		in += pg_mblen(in);
+
+	if (!*in || *in == '#')
+		return NULL;
+	start = in;
+
+	while (*in && !t_isspace(in))
+		in += pg_mblen(in);
+
+	*end = in;
+
+	return start;
+}
+
+static int
+compare_syn(const void *a, const void *b)
+{
+	return strcmp(((Syn *) a)->key, ((Syn *) b)->key);
+}
+
+static void
+read_dictionary(DictSyn *d, char *filename)
+{
+	char *real_filename = get_tsearch_config_filename(filename, "rules");
+	FILE *fin;
+	char *line;
+	int cur = 0;
+
+	if ((fin = AllocateFile(real_filename, "r")) == NULL)
+		ereport(ERROR,
+				(errcode(ERRCODE_CONFIG_FILE_ERROR),
+				 errmsg("could not open synonym file \"%s\": %m",
+						real_filename)));
+
+	while ((line = t_readline(fin)) != NULL)
+	{
+		char *value;
+		char *key;
+		char *end = NULL;
+
+		if (*line == '\0')
+			continue;
+
+		value = lowerstr(line);
+		pfree(line);
+
+		key = find_word(value, &end);
+		if (!key)
+		{
+			pfree(value);
+			continue;
+		}
+
+		if (cur == d->len)
+		{
+			d->len = (d->len > 0) ? 2 * d->len : 16;
+			if (d->syn)
+				d->syn = (Syn *) repalloc(d->syn, sizeof(Syn) * d->len);
+			else
+				d->syn = (Syn *) palloc(sizeof(Syn) * d->len);
+		}
+
+		d->syn[cur].key = pnstrdup(key, end - key);
+		d->syn[cur].value = value;
+
+		cur++;
+	}
+
+	FreeFile(fin);
+
+	d->len = cur;
+	if (cur > 1)
+		qsort(d->syn, d->len, sizeof(Syn), compare_syn);
+
+	pfree(real_filename);
+}
+
+Datum
+dxsyn_init(PG_FUNCTION_ARGS)
+{
+	List *dictoptions = (List *) PG_GETARG_POINTER(0);
+	DictSyn *d;
+	ListCell *l;
+
+	d = (DictSyn *) palloc0(sizeof(DictSyn));
+	d->len = 0;
+	d->syn = NULL;
+	d->keeporig = true;
+
+	foreach(l, dictoptions)
+	{
+		DefElem *defel = (DefElem *) lfirst(l);
+
+		if (pg_strcasecmp(defel->defname, "KEEPORIG") == 0)
+		{
+			d->keeporig = defGetBoolean(defel);
+		}
+		else if (pg_strcasecmp(defel->defname, "RULES") == 0)
+		{
+			read_dictionary(d, defGetString(defel));
+		}
+		else
+		{
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					 errmsg("unrecognized xsyn parameter: \"%s\"",
+							defel->defname)));
+		}
+	}
+
+	PG_RETURN_POINTER(d);
+}
+
+Datum
+dxsyn_lexize(PG_FUNCTION_ARGS)
+{
+	DictSyn *d = (DictSyn *) PG_GETARG_POINTER(0);
+	char *in = (char *) PG_GETARG_POINTER(1);
+	int length = PG_GETARG_INT32(2);
+	Syn word;
+	Syn *found;
+	TSLexeme *res = NULL;
+
+	if (!length || d->len == 0)
+		PG_RETURN_POINTER(NULL);
+
+	/* Create search pattern */
+	{
+		char *temp = pnstrdup(in, length);
+
+		word.key = lowerstr(temp);
+		pfree(temp);
+		word.value = NULL;
+	}
+
+	/* Look for matching syn */
+	found = (Syn *)bsearch(&word, d->syn, d->len, sizeof(Syn), compare_syn);
+	pfree(word.key);
+
+	if (!found)
+		PG_RETURN_POINTER(NULL);
+
+	/* Parse string of synonyms and return array of words */
+	{
+		char *value = pstrdup(found->value);
+		int value_length = strlen(value);
+		char *pos = value;
+		int nsyns = 0;
+		bool is_first = true;
+
+		res = palloc(0);
+
+		while(pos < value + value_length)
+		{
+			char *end;
+			char *syn = find_word(pos, &end);
+
+			if (!syn)
+				break;
+			*end = '\0';
+
+			res = repalloc(res, sizeof(TSLexeme)*(nsyns + 2));
+			res[nsyns].lexeme = NULL;
+
+			/* first word is added to result only if KEEPORIG flag is set */
+			if(d->keeporig || !is_first)
+			{
+				res[nsyns].lexeme = pstrdup(syn);
+				res[nsyns + 1].lexeme = NULL;
+
+				nsyns++;
+			}
+
+			is_first = false;
+
+			pos = end + 1;
+		}
+
+		pfree(value);
+	}
+
+	PG_RETURN_POINTER(res);
+}

contrib/dict_xsyn/dict_xsyn.sql.in

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+-- $PostgreSQL: pgsql/contrib/dict_xsyn/dict_xsyn.sql.in,v 1.1 2007/10/15 21:36:50 tgl Exp $
+
+-- Adjust this setting to control where the objects get created.
+SET search_path = public;
+
+BEGIN;
+
+CREATE FUNCTION dxsyn_init(internal)
+        RETURNS internal
+        AS 'MODULE_PATHNAME'
+        LANGUAGE C STRICT;
+
+CREATE FUNCTION dxsyn_lexize(internal, internal, internal, internal)
+        RETURNS internal
+        AS 'MODULE_PATHNAME'
+        LANGUAGE C STRICT;
+
+CREATE TEXT SEARCH TEMPLATE xsyn_template (
+        LEXIZE = dxsyn_lexize,
+	INIT   = dxsyn_init
+);
+
+CREATE TEXT SEARCH DICTIONARY xsyn (
+	TEMPLATE = xsyn_template
+);
+
+COMMENT ON TEXT SEARCH DICTIONARY xsyn IS 'eXtended synonym dictionary';
+
+END;

contrib/dict_xsyn/expected/dict_xsyn.out

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+--
+-- first, define the datatype.  Turn off echoing so that expected file
+-- does not depend on contents of this file.
+--
+SET client_min_messages = warning;
+\set ECHO none
+RESET client_min_messages;
+--configuration
+ALTER TEXT SEARCH DICTIONARY xsyn (RULES='xsyn_sample', KEEPORIG=false);
+--lexize
+SELECT ts_lexize('xsyn', 'supernova');
+   ts_lexize    
+----------------
+ {sn,sne,1987a}
+(1 row)
+
+SELECT ts_lexize('xsyn', 'grb');
+ ts_lexize 
+-----------
+ 
+(1 row)
+

contrib/dict_xsyn/sql/dict_xsyn.sql

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+--
+-- first, define the datatype.  Turn off echoing so that expected file
+-- does not depend on contents of this file.
+--
+SET client_min_messages = warning;
+\set ECHO none
+\i dict_xsyn.sql
+\set ECHO all
+RESET client_min_messages;
+
+--configuration
+ALTER TEXT SEARCH DICTIONARY xsyn (RULES='xsyn_sample', KEEPORIG=false);
+
+--lexize
+SELECT ts_lexize('xsyn', 'supernova');
+SELECT ts_lexize('xsyn', 'grb');

contrib/dict_xsyn/uninstall_dict_xsyn.sql

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+SET search_path = public;
+
+DROP TEXT SEARCH DICTIONARY xsyn;
+
+DROP TEXT SEARCH TEMPLATE xsyn_template;
+
+DROP FUNCTION dxsyn_init(internal);
+
+DROP FUNCTION dxsyn_lexize(internal,internal,internal,internal);

contrib/dict_xsyn/xsyn_sample.rules

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+# Sample rules file for eXtended Synonym (xsyn) dictionary
+# format is as follows:
+#
+# word synonym1 synonym2 ...
+#
+supernova sn sne 1987a