diff options
Diffstat (limited to 'build.zig')
| -rw-r--r-- | build.zig | 35 |
1 files changed, 34 insertions, 1 deletions
@@ -454,7 +454,40 @@ pub fn build(b: *std.Build) void { \\pub threadlocal var exhausted: bool = false; \\ ; - const patched = b.fmt("{s}{s}{s}{s}", .{ src[0..at], spend, src[at..], budget }); + const budgeted = b.fmt("{s}{s}{s}{s}", .{ src[0..at], spend, src[at..], budget }); + // A group's greedy match never gave back to what follows the group: + // on `aab`, `(a+)ab` missed where `a+ab` matched. hasAlt counts the + // group's own `)` as an alternative, so every group with pattern + // after it takes matchGroup's alternatives branch, which tries each + // alternative's one (greedy) match and gives up. When the rest fails + // after it, try that alternative's shorter matches, longest first + // (docs/mvzr-group-backtrack.md is the report for upstream). + const group_anchor = + \\ const next_match = matchPattern(next_patt, sets, haystack, m1.i); + \\ if (next_match) |m2| { + \\ // Whole group matches, and we can use m2.j + \\ return m2; + \\ } else { // Try our next pattern, if any. + \\ + ; + const group_backoff = + \\ const next_match = matchPattern(next_patt, sets, haystack, m1.i); + \\ if (next_match) |m2| { + \\ // Whole group matches, and we can use m2.j + \\ return m2; + \\ } else { // Try our next pattern, if any. + \\ // pardes's patch (its build.zig): back the group off. + \\ var e = m1.i; + \\ while (e > i) { + \\ e -= 1; + \\ const shorter = matchAlt(remaining_patt, sets, haystack[0..e], i) orelse continue; + \\ if (shorter.i != e) continue; + \\ if (matchPattern(next_patt, sets, haystack, e)) |whole| return whole; + \\ } + \\ + ; + if (std.mem.count(u8, budgeted, group_anchor) != 1) @panic("mvzr's matchGroup changed: redo its group backtracking in build.zig"); + const patched = std.mem.replaceOwned(u8, b.allocator, budgeted, group_anchor, group_backoff) catch @panic("OOM"); break :mvzr b.createModule(.{ .root_source_file = b.addWriteFiles().add("mvzr.zig", patched), .target = target, .optimize = optimize }); }; |