tiny.zen.html

1const std = @import("std");23const Allocator = std.mem.Allocator;45pub fn appendEscaped(out: *std.ArrayList(u8), allocator: Allocator, value: []const u8) Allocator.Error!void {6    for (value) |byte| try appendEscapedByte(out, allocator, byte);7}89pub fn appendAttributeEscaped(out: *std.ArrayList(u8), allocator: Allocator, value: []const u8) Allocator.Error!void {10    try appendEscaped(out, allocator, value);11}1213pub fn appendEscapedByte(out: *std.ArrayList(u8), allocator: Allocator, byte: u8) Allocator.Error!void {14    switch (byte) {15        '&' => try out.appendSlice(allocator, "&amp;"),16        '<' => try out.appendSlice(allocator, "&lt;"),17        '>' => try out.appendSlice(allocator, "&gt;"),18        '"' => try out.appendSlice(allocator, "&quot;"),19        '\'' => try out.appendSlice(allocator, "&#39;"),20        else => try out.append(allocator, byte),21    }22}2324pub fn escapedLength(value: []const u8) error{CapacityOverflow}!usize {25    var length: usize = 0;26    for (value) |byte| {27        length = std.math.add(usize, length, escapedByteLength(byte)) catch28            return error.CapacityOverflow;29    }30    return length;31}3233pub fn writeEscaped(out: []u8, value: []const u8) []u8 {34    const length = escapedLength(value) catch unreachable;35    std.debug.assert(out.len >= length);36    var index: usize = 0;37    for (value) |byte| switch (byte) {38        '&' => copy(out, &index, "&amp;"),39        '<' => copy(out, &index, "&lt;"),40        '>' => copy(out, &index, "&gt;"),41        '"' => copy(out, &index, "&quot;"),42        '\'' => copy(out, &index, "&#39;"),43        else => {44            out[index] = byte;45            index += 1;46        },47    };48    std.debug.assert(index == length);49    return out[0..index];50}5152pub fn escapedAlloc(allocator: Allocator, value: []const u8) Allocator.Error![]u8 {53    var out: std.ArrayList(u8) = .empty;54    errdefer out.deinit(allocator);55    try appendEscaped(&out, allocator, value);56    return try out.toOwnedSlice(allocator);57}5859pub fn slug(allocator: Allocator, value: []const u8) Allocator.Error![]u8 {60    const out = try allocator.alloc(u8, slugLength(value));61    _ = writeSlug(out, value);62    return out;63}6465pub fn slugLength(value: []const u8) usize {66    var length: usize = 0;67    var previous_dash = false;6869    for (value) |byte| {70        if (isAsciiAlnum(byte)) {71            length += 1;72            previous_dash = false;73        } else if (byte == ' ' or byte == '\t' or byte == '-' or byte == '_') {74            if (!previous_dash and length != 0) {75                length += 1;76                previous_dash = true;77            }78        }79    }8081    if (length != 0 and previous_dash) length -= 1;82    return if (length == 0) "section".len else length;83}8485pub fn writeSlug(out: []u8, value: []const u8) []u8 {86    std.debug.assert(out.len >= slugLength(value));87    var index: usize = 0;88    var pending_dash = false;8990    for (value) |byte| {91        if (isAsciiAlnum(byte)) {92            if (pending_dash) {93                out[index] = '-';94                index += 1;95            }96            out[index] = std.ascii.toLower(byte);97            index += 1;98            pending_dash = false;99        } else if (byte == ' ' or byte == '\t' or byte == '-' or byte == '_') {100            if (index != 0) pending_dash = true;101        }102    }103104    if (index == 0) {105        @memcpy(out[0.."section".len], "section");106        index = "section".len;107    }108    std.debug.assert(index == slugLength(value));109    return out[0..index];110}111112fn isAsciiAlnum(byte: u8) bool {113    return (byte >= 'a' and byte <= 'z') or114        (byte >= 'A' and byte <= 'Z') or115        (byte >= '0' and byte <= '9');116}117118fn escapedByteLength(byte: u8) usize {119    return switch (byte) {120        '&' => "&amp;".len,121        '<' => "&lt;".len,122        '>' => "&gt;".len,123        '"' => "&quot;".len,124        '\'' => "&#39;".len,125        else => 1,126    };127}128129fn copy(out: []u8, index: *usize, value: []const u8) void {130    @memcpy(out[index.*..][0..value.len], value);131    index.* += value.len;132}133134test "html escaping covers text and attributes" {135    const escaped = try escapedAlloc(std.testing.allocator, "<a href=\"x&y\">'");136    defer std.testing.allocator.free(escaped);137    try std.testing.expectEqualStrings("&lt;a href=&quot;x&amp;y&quot;&gt;&#39;", escaped);138    var exact: [44]u8 = undefined;139    const written = writeEscaped(&exact, "<a href=\"x&y\">'");140    try std.testing.expectEqual(try escapedLength("<a href=\"x&y\">'"), written.len);141    try std.testing.expectEqualStrings(escaped, written);142}143144test "slug normalizes ascii heading text" {145    const value = try slug(std.testing.allocator, "Fast, Robust Sites!");146    defer std.testing.allocator.free(value);147    try std.testing.expectEqualStrings("fast-robust-sites", value);148}149150test "slug length and caller storage cover fallback and trailing separators" {151    var normal: [17]u8 = undefined;152    try std.testing.expectEqualStrings(153        "fast-robust-sites",154        writeSlug(&normal, "Fast, Robust Sites!--"),155    );156    var fallback: [7]u8 = undefined;157    try std.testing.expectEqualStrings("section", writeSlug(&fallback, "!?"));158    try std.testing.expectEqual(@as(usize, 7), slugLength("!?"));159}

1/// HTML text and attribute escaping helpers.2pub const html = @import("html.zig");