1 files changed, 292 insertions, 0 deletions
diff --git a/src/backend/regex/regexport.c b/src/backend/regex/regexport.c
new file mode 100644
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+++ b/src/backend/regex/regexport.c
@@ -0,0 +1,292 @@
+/*-------------------------------------------------------------------------
+ *
+ * regexport.c
+ *	  Functions for exporting info about a regex's NFA
+ *
+ * In this implementation, the NFA defines a necessary but not sufficient
+ * condition for a string to match the regex: that is, there can be strings
+ * that match the NFA but don't match the full regex, but not vice versa.
+ * Thus, for example, it is okay for the functions below to ignore lookahead
+ * constraints, which merely constrain the string some more.
+ *
+ * Notice that these functions return info into caller-provided arrays
+ * rather than doing their own malloc's.  This simplifies the APIs by
+ * eliminating a class of error conditions, and in the case of colors
+ * allows the caller to decide how big is too big to bother with.
+ *
+ *
+ * Portions Copyright (c) 2013, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1998, 1999 Henry Spencer
+ *
+ * IDENTIFICATION
+ *	  src/backend/regex/regexport.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "regex/regguts.h"
+
+#include "regex/regexport.h"
+
+static void scancolormap(struct colormap * cm, int co,
+			 union tree * t, int level, chr partial,
+			 pg_wchar **chars, int *chars_len);
+
+
+/*
+ * Get total number of NFA states.
+ */
+int
+pg_reg_getnumstates(const regex_t *regex)
+{
+	struct cnfa *cnfa;
+
+	assert(regex != NULL && regex->re_magic == REMAGIC);
+	cnfa = &((struct guts *) regex->re_guts)->search;
+
+	return cnfa->nstates;
+}
+
+/*
+ * Get initial state of NFA.
+ */
+int
+pg_reg_getinitialstate(const regex_t *regex)
+{
+	struct cnfa *cnfa;
+
+	assert(regex != NULL && regex->re_magic == REMAGIC);
+	cnfa = &((struct guts *) regex->re_guts)->search;
+
+	return cnfa->pre;
+}
+
+/*
+ * Get final state of NFA.
+ */
+int
+pg_reg_getfinalstate(const regex_t *regex)
+{
+	struct cnfa *cnfa;
+
+	assert(regex != NULL && regex->re_magic == REMAGIC);
+	cnfa = &((struct guts *) regex->re_guts)->search;
+
+	return cnfa->post;
+}
+
+/*
+ * Get number of outgoing NFA arcs of state number "st".
+ *
+ * Note: LACON arcs are ignored, both here and in pg_reg_getoutarcs().
+ */
+int
+pg_reg_getnumoutarcs(const regex_t *regex, int st)
+{
+	struct cnfa *cnfa;
+	struct carc *ca;
+	int			count;
+
+	assert(regex != NULL && regex->re_magic == REMAGIC);
+	cnfa = &((struct guts *) regex->re_guts)->search;
+
+	if (st < 0 || st >= cnfa->nstates)
+		return 0;
+	count = 0;
+	for (ca = cnfa->states[st]; ca->co != COLORLESS; ca++)
+	{
+		if (ca->co < cnfa->ncolors)
+			count++;
+	}
+	return count;
+}
+
+/*
+ * Write array of outgoing NFA arcs of state number "st" into arcs[],
+ * whose length arcs_len must be at least as long as indicated by
+ * pg_reg_getnumoutarcs(), else not all arcs will be returned.
+ */
+void
+pg_reg_getoutarcs(const regex_t *regex, int st,
+				  regex_arc_t *arcs, int arcs_len)
+{
+	struct cnfa *cnfa;
+	struct carc *ca;
+
+	assert(regex != NULL && regex->re_magic == REMAGIC);
+	cnfa = &((struct guts *) regex->re_guts)->search;
+
+	if (st < 0 || st >= cnfa->nstates || arcs_len <= 0)
+		return;
+	for (ca = cnfa->states[st]; ca->co != COLORLESS; ca++)
+	{
+		if (ca->co < cnfa->ncolors)
+		{
+			arcs->co = ca->co;
+			arcs->to = ca->to;
+			arcs++;
+			if (--arcs_len == 0)
+				break;
+		}
+	}
+}
+
+/*
+ * Get total number of colors.
+ */
+int
+pg_reg_getnumcolors(const regex_t *regex)
+{
+	struct colormap *cm;
+
+	assert(regex != NULL && regex->re_magic == REMAGIC);
+	cm = &((struct guts *) regex->re_guts)->cmap;
+
+	return cm->max + 1;
+}
+
+/*
+ * Check if color is beginning of line/string.
+ *
+ * (We might at some point need to offer more refined handling of pseudocolors,
+ * but this will do for now.)
+ */
+int
+pg_reg_colorisbegin(const regex_t *regex, int co)
+{
+	struct cnfa *cnfa;
+
+	assert(regex != NULL && regex->re_magic == REMAGIC);
+	cnfa = &((struct guts *) regex->re_guts)->search;
+
+	if (co == cnfa->bos[0] || co == cnfa->bos[1])
+		return true;
+	else
+		return false;
+}
+
+/*
+ * Check if color is end of line/string.
+ */
+int
+pg_reg_colorisend(const regex_t *regex, int co)
+{
+	struct cnfa *cnfa;
+
+	assert(regex != NULL && regex->re_magic == REMAGIC);
+	cnfa = &((struct guts *) regex->re_guts)->search;
+
+	if (co == cnfa->eos[0] || co == cnfa->eos[1])
+		return true;
+	else
+		return false;
+}
+
+/*
+ * Get number of member chrs of color number "co".
+ *
+ * Note: we return -1 if the color number is invalid, or if it is a special
+ * color (WHITE or a pseudocolor), or if the number of members is uncertain.
+ * The latter case cannot arise right now but is specified to allow for future
+ * improvements (see musings about run-time handling of higher character codes
+ * in regex/README).  Callers should not try to extract the members if -1 is
+ * returned.
+ */
+int
+pg_reg_getnumcharacters(const regex_t *regex, int co)
+{
+	struct colormap *cm;
+
+	assert(regex != NULL && regex->re_magic == REMAGIC);
+	cm = &((struct guts *) regex->re_guts)->cmap;
+
+	if (co <= 0 || co > cm->max)	/* we reject 0 which is WHITE */
+		return -1;
+	if (cm->cd[co].flags & PSEUDO)		/* also pseudocolors (BOS etc) */
+		return -1;
+
+	return cm->cd[co].nchrs;
+}
+
+/*
+ * Write array of member chrs of color number "co" into chars[],
+ * whose length chars_len must be at least as long as indicated by
+ * pg_reg_getnumcharacters(), else not all chars will be returned.
+ *
+ * Fetching the members of WHITE or a pseudocolor is not supported.
+ *
+ * Caution: this is a relatively expensive operation.
+ */
+void
+pg_reg_getcharacters(const regex_t *regex, int co,
+					 pg_wchar *chars, int chars_len)
+{
+	struct colormap *cm;
+
+	assert(regex != NULL && regex->re_magic == REMAGIC);
+	cm = &((struct guts *) regex->re_guts)->cmap;
+
+	if (co <= 0 || co > cm->max || chars_len <= 0)
+		return;
+	if (cm->cd[co].flags & PSEUDO)
+		return;
+
+	/* Recursively search the colormap tree */
+	scancolormap(cm, co, cm->tree, 0, 0, &chars, &chars_len);
+}
+
+/*
+ * Recursively scan the colormap tree to find chrs belonging to color "co".
+ * See regex/README for info about the tree structure.
+ *
+ * t: tree block to scan
+ * level: level (from 0) of t
+ * partial: partial chr code for chrs within t
+ * chars, chars_len: output area
+ */
+static void
+scancolormap(struct colormap * cm, int co,
+			 union tree * t, int level, chr partial,
+			 pg_wchar **chars, int *chars_len)
+{
+	int			i;
+
+	if (level < NBYTS - 1)
+	{
+		/* non-leaf node */
+		for (i = 0; i < BYTTAB; i++)
+		{
+			/*
+			 * We do not support search for chrs of color 0 (WHITE), so
+			 * all-white subtrees need not be searched.  These can be
+			 * recognized because they are represented by the fill blocks in
+			 * the colormap struct.  This typically allows us to avoid
+			 * scanning large regions of higher-numbered chrs.
+			 */
+			if (t->tptr[i] == &cm->tree[level + 1])
+				continue;
+
+			/* Recursively scan next level down */
+			scancolormap(cm, co,
+						 t->tptr[i], level + 1,
+						 (partial | (chr) i) << BYTBITS,
+						 chars, chars_len);
+		}
+	}
+	else
+	{
+		/* leaf node */
+		for (i = 0; i < BYTTAB; i++)
+		{
+			if (t->tcolor[i] == co)
+			{
+				if (*chars_len > 0)
+				{
+					**chars = partial | (chr) i;
+					(*chars)++;
+					(*chars_len)--;
+				}
+			}
+		}
+	}
+}