diff-zimilar

a port of dtolnay/dissimilar text diffing library to zig. includes semantic cleanups. based on google's diff match patch.

goals

• reduced memory footprint, limited allocations
• fast diffing, maybe for use in zls

tools

diffit

a simple diffing utility that can be run from the command line:

$ zig build run -- <file_a> <file_b>

$ zig build && zig-out/bin/diffit <file_a> <file_b>

this shows ansi colored diffs.

benchmark

$ zig run -lc -OReleaseFast src/bench.zig -- <file_a> <file_b> <iterations>

$ zig  run -lc -OReleaseFast src/bench.zig -- /tmp/dissimilar/benches/document1.txt /tmp/dissimilar/benches/document2.txt 10
took 1.363s for 10 diffs

usage

test {
    const diff = @import("lib.zig");
    var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
    const aalloc = arena.allocator();
    // 'catch return' just allows test to pass
    const file_a = std.fs.cwd().openFile("/path/to/file_a", .{}) catch return; 
    const file_b = std.fs.cwd().openFile("/path/to/file_b", .{}) catch return;
    const doc_a = try file_a.readToEndAlloc(aalloc, std.math.maxInt(u32));
    const doc_b = try file_b.readToEndAlloc(aalloc, std.math.maxInt(u32));
    var chunks = try diff.diff(aalloc, doc_a, doc_b);
    defer chunks.deinit(aalloc);
}

references

• inspired by tomhoule/zig-diff
• ported from dtolnay/dissimilar
• google diff match patch
• Myers' diff algorithm
• semantic cleanups