Initial revision

src/cmd/mk/lex.c

@@ -0,0 +1,147 @@
+#include	"mk.h"
+
+static	int	bquote(Biobuf*, Bufblock*);
+
+/*
+ *	Assemble a line skipping blank lines, comments, and eliding
+ *	escaped newlines
+ */
+int
+assline(Biobuf *bp, Bufblock *buf)
+{
+	int c;
+	int lastc;
+
+	buf->current=buf->start;
+	while ((c = nextrune(bp, 1)) >= 0){
+		switch(c)
+		{
+		case '\r':		/* consumes CRs for Win95 */
+			continue;
+		case '\n':
+			if (buf->current != buf->start) {
+				insert(buf, 0);
+				return 1;
+			}
+			break;		/* skip empty lines */
+		case '\\':
+		case '\'':
+		case '"':
+			rinsert(buf, c);
+			if (escapetoken(bp, buf, 1, c) == 0)
+				Exit();
+			break;
+		case '`':
+			if (bquote(bp, buf) == 0)
+				Exit();
+			break;
+		case '#':
+			lastc = '#';
+			while ((c = Bgetc(bp)) != '\n') {
+				if (c < 0)
+					goto eof;
+				if(c != '\r')
+					lastc = c;
+			}
+			mkinline++;
+			if (lastc == '\\')
+				break;		/* propagate escaped newlines??*/
+			if (buf->current != buf->start) {
+				insert(buf, 0);
+				return 1;
+			}
+			break;
+		default:
+			rinsert(buf, c);
+			break;
+		}
+	}
+eof:
+	insert(buf, 0);
+	return *buf->start != 0;
+}
+
+/*
+ *	assemble a back-quoted shell command into a buffer
+ */
+static int
+bquote(Biobuf *bp, Bufblock *buf)
+{
+	int c, line, term;
+	int start;
+
+	line = mkinline;
+	while((c = Bgetrune(bp)) == ' ' || c == '\t')
+			;
+	if(c == '{'){
+		term = '}';		/* rc style */
+		while((c = Bgetrune(bp)) == ' ' || c == '\t')
+			;
+	} else
+		term = '`';		/* sh style */
+
+	start = buf->current-buf->start;
+	for(;c > 0; c = nextrune(bp, 0)){
+		if(c == term){
+			insert(buf, '\n');
+			insert(buf,0);
+			buf->current = buf->start+start;
+			execinit();
+			execsh(0, buf->current, buf, envy);
+			return 1;
+		}
+		if(c == '\n')
+			break;
+		if(c == '\'' || c == '"' || c == '\\'){
+			insert(buf, c);
+			if(!escapetoken(bp, buf, 1, c))
+				return 0;
+			continue;
+		}
+		rinsert(buf, c);
+	}
+	SYNERR(line);
+	fprint(2, "missing closing %c after `\n", term);
+	return 0;
+}
+
+/*
+ *	get next character stripping escaped newlines
+ *	the flag specifies whether escaped newlines are to be elided or
+ *	replaced with a blank.
+ */
+int
+nextrune(Biobuf *bp, int elide)
+{
+	int c, c2;
+	static int savec;
+
+	if(savec){
+		c = savec;
+		savec = 0;
+		return c;
+	}
+
+	for (;;) {
+		c = Bgetrune(bp);
+		if (c == '\\') {
+			c2 = Bgetrune(bp);
+			if(c2 == '\r'){
+				savec = c2;
+				c2 = Bgetrune(bp);
+			}
+			if (c2 == '\n') {
+				savec = 0;
+				mkinline++;
+				if (elide)
+					continue;
+				return ' ';
+			}
+			Bungetrune(bp);
+		}
+		if (c == '\n')
+			mkinline++;
+		return c;
+	}
+	return 0;
+}