Initial revision

1 files changed, 99 insertions, 0 deletions

diff --git a/match.c b/match.c
new file mode 100644
index 0000000..6f87614
--- /dev/null
+++ b/match.c
@@ -0,0 +1,99 @@
+/* match.c: pattern matching routines */
+
+#include "rc.h"
+
+static int rangematch(char *, char);
+
+enum { RANGE_FAIL = -1, RANGE_ERROR = -2 };
+
+/* match() matches a single pattern against a single string. */
+
+extern bool match(char *p, char *m, char *s) {
+	int i, j;
+	if (m == NULL)
+		return streq(p, s);
+	i = 0;
+	while (1) {
+		if (p[i] == '\0')
+			return *s == '\0';
+		else if (m[i]) {
+			switch (p[i++]) {
+			case '?':
+				if (*s++ == '\0')
+					return FALSE;
+				break;
+			case '*':
+				while (p[i] == '*' && m[i] == 1)	/* collapse multiple stars */
+					i++;
+				if (p[i] == '\0') 	/* star at end of pattern? */
+					return TRUE;
+				while (*s != '\0')
+					if (match(p + i, m + i, s++))
+						return TRUE;
+				return FALSE;
+			case '[':
+				if (*s == '\0')
+					return FALSE;
+				switch (j = rangematch(p + i, *s)) {
+				default:
+					i += j;
+					break;
+				case RANGE_FAIL:
+					return FALSE;
+				case RANGE_ERROR:
+					if (*s != '[')
+						return FALSE;
+				}
+				s++;
+				break;
+			default:
+				panic("bad metacharacter in match");
+				/* NOTREACHED */
+				return FALSE; /* hush up gcc -Wall */
+			}
+		} else if (p[i++] != *s++)
+			return FALSE;
+	}
+}
+
+/*
+   From the ed(1) man pages (on ranges):
+
+	The `-' is treated as an ordinary character if it occurs first
+	(or first after an initial ^) or last in the string.
+
+	The right square bracket does not terminate the enclosed string
+	if it is the first character (after an initial `^', if any), in
+	the bracketed string.
+
+   rangematch() matches a single character against a class, and returns
+   an integer offset to the end of the range on success, or -1 on
+   failure.
+*/
+
+static int rangematch(char *p, char c) {
+	char *orig = p;
+	bool neg = (*p == '~');
+	bool matched = FALSE;
+	if (neg)
+		p++;
+	if (*p == ']') {
+		p++;
+		matched = (c == ']');
+	}
+	for (; *p != ']'; p++) {
+		if (*p == '\0')
+			return RANGE_ERROR;	/* bad syntax */
+		if (p[1] == '-' && p[2] != ']') { /* check for [..-..] but ignore [..-] */
+			if (c >= *p)
+				matched |= (c <= p[2]);
+			p += 2;
+		} else {
+			matched |= (*p == c);
+		}
+	}
+	if (matched ^ neg)
+		return p - orig + 1; /* skip the right-bracket */
+	else
+		return RANGE_FAIL;
+}