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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147const std = @import("std");
/// Parse a string literal into a byte array. The string can contain/// any valid Zig string literal escape sequences.////// The output buffer never needs to be larger than the input buffer./// The buffers may alias.pub fn parse(out: []u8, bytes: []const u8) ![]u8 { var dst_i: usize = 0; var src_i: usize = 0; while (src_i < bytes.len) { if (dst_i >= out.len) return error.OutOfMemory;
// If this byte is not beginning an escape sequence we copy. const b = bytes[src_i]; if (b != '\\') { out[dst_i] = b; dst_i += 1; src_i += 1; continue; }
// Parse the escape sequence switch (std.zig.string_literal.parseEscapeSequence( bytes, &src_i, )) { .failure => return error.InvalidString, .success => |cp| dst_i += try std.unicode.utf8Encode( cp, out[dst_i..], ), } }
return out[0..dst_i];}
/// Creates an iterator that requires no allocation to extract codepoints/// from the string literal, parsing escape sequences as it goes.pub fn codepointIterator(bytes: []const u8) CodepointIterator { return .{ .bytes = bytes, .i = 0 };}
pub const CodepointIterator = struct { bytes: []const u8, i: usize,
pub fn next(self: *CodepointIterator) error{InvalidString}!?u21 { if (self.i >= self.bytes.len) return null; switch (self.bytes[self.i]) { // An escape sequence '\\' => return switch (std.zig.string_literal.parseEscapeSequence( self.bytes, &self.i, )) { .failure => error.InvalidString, .success => |cp| cp, },
// Not an escape, parse as UTF-8 else => |start| { const cp_len = std.unicode.utf8ByteSequenceLength(start) catch return error.InvalidString; defer self.i += cp_len; return std.unicode.utf8Decode(self.bytes[self.i..][0..cp_len]) catch return error.InvalidString; }, } }};
test "parse: empty" { const testing = std.testing;
var buf: [128]u8 = undefined; const result = try parse(&buf, ""); try testing.expectEqualStrings("", result);}
test "parse: no escapes" { const testing = std.testing;
var buf: [128]u8 = undefined; const result = try parse(&buf, "hello world"); try testing.expectEqualStrings("hello world", result);}
test "parse: escapes" { const testing = std.testing;
var buf: [128]u8 = undefined; { const result = try parse(&buf, "hello\\nworld"); try testing.expectEqualStrings("hello\nworld", result); } { const result = try parse(&buf, "hello\\u{1F601}world"); try testing.expectEqualStrings("hello\u{1F601}world", result); }}
test "codepointIterator: empty" { var it = codepointIterator(""); try std.testing.expectEqual(null, try it.next());}
test "codepointIterator: ascii no escapes" { var it = codepointIterator("abc"); try std.testing.expectEqual(@as(u21, 'a'), (try it.next()).?); try std.testing.expectEqual(@as(u21, 'b'), (try it.next()).?); try std.testing.expectEqual(@as(u21, 'c'), (try it.next()).?); try std.testing.expectEqual(null, try it.next());}
test "codepointIterator: multibyte utf8" { // │ is U+2502 (3 bytes in UTF-8) var it = codepointIterator("a│b"); try std.testing.expectEqual(@as(u21, 'a'), (try it.next()).?); try std.testing.expectEqual(@as(u21, '│'), (try it.next()).?); try std.testing.expectEqual(@as(u21, 'b'), (try it.next()).?); try std.testing.expectEqual(null, try it.next());}
test "codepointIterator: escape sequences" { var it = codepointIterator("a\\tb\\n\\\\"); try std.testing.expectEqual(@as(u21, 'a'), (try it.next()).?); try std.testing.expectEqual(@as(u21, '\t'), (try it.next()).?); try std.testing.expectEqual(@as(u21, 'b'), (try it.next()).?); try std.testing.expectEqual(@as(u21, '\n'), (try it.next()).?); try std.testing.expectEqual(@as(u21, '\\'), (try it.next()).?); try std.testing.expectEqual(null, try it.next());}
test "codepointIterator: unicode escape" { var it = codepointIterator("\\u{2502}x"); try std.testing.expectEqual(@as(u21, '│'), (try it.next()).?); try std.testing.expectEqual(@as(u21, 'x'), (try it.next()).?); try std.testing.expectEqual(null, try it.next());}
test "codepointIterator: emoji unicode escape" { var it = codepointIterator("\\u{1F601}"); try std.testing.expectEqual(@as(u21, 0x1F601), (try it.next()).?); try std.testing.expectEqual(null, try it.next());}