hare

commit 5e8b42336bdb6196dcac7ba5facf4a4fb1f98c88
parent c9a7e680b20833937ad85a6dc3e020ffdbcf0067
Author: Eyal Sawady <ecs@d2evs.net>
Date:   Fri, 28 May 2021 11:45:06 -0400

lex::prevloc: add

Signed-off-by: Eyal Sawady <ecs@d2evs.net>

Diffstat:
M
hare/lex/lex.ha
 | 
23
+++++++++++++++++++++++

1 file changed, 23 insertions(+), 0 deletions(-)
diff --git a/hare/lex/lex.ha b/hare/lex/lex.ha
@@ -15,6 +15,9 @@ export type lexer = struct {
 	loc: (uint, uint),
 	un: (token | void),
 	rb: [2]((rune, location) | io::EOF | void),
+	// 1 more than the size of un and rb respectively
+	prevunlocs: [2](location, location),
+	prevrlocs: [3]location,
 	flags: flags,
 	comment: str,
 };
@@ -47,12 +50,15 @@ export fn init(in: *io::stream, path: str, flags: flags...) lexer = {
 	for (let i = 0z; i < len(flags); i += 1) {
 		f |= flags[i];
 	};
+	const loc = location { path = path, line = 1, col = 1 };
 	return lexer {
 		in = in,
 		path = path,
 		loc = (1, 1),
 		un = void,
 		rb = [void...],
+		prevunlocs = [(loc, loc)...],
+		prevrlocs = [loc...],
 		flags = f,
 		comment = "",
 	};
@@ -72,6 +78,11 @@ export fn lex(lex: *lexer) (token | error) = {
 		void => void,
 	};
 
+	defer {
+		lex.prevunlocs[1] = lex.prevunlocs[0];
+		lex.prevunlocs[0] = (prevloc(lex), mkloc(lex));
+	};
+
 	let r = match (nextw(lex)?) {
 		io::EOF => return (ltok::EOF, void, mkloc(lex)),
 		r: (rune, location) => r,
@@ -623,6 +634,9 @@ fn next(lex: *lexer) ((rune, location) | io::EOF | io::error) = {
 		e: (io::EOF | io::error) => e,
 		r: rune => {
 			const loc = mkloc(lex);
+			let tmp = lex.prevrlocs;
+			lex.prevrlocs[1..] = tmp[..len(tmp) - 1];
+			lex.prevrlocs[0] = loc;
 			lexloc(lex, r);
 			return (r, loc);
 		},
@@ -684,4 +698,13 @@ export fn mkloc(lex: *lexer) location = match (lex.rb[0]) {
 	},
 };
 
+export fn prevloc(lex: *lexer) location = match (lex.un) {
+	t: token => lex.prevunlocs[1].0,
+	void => {
+		let i = 0z;
+		for (i < len(lex.rb); i += 1) if (lex.rb[i] is void) break;
+		return lex.prevrlocs[i];
+	},
+};
+
 fn syntaxerr(loc: location, why: str) error = (loc, why);