tiny.css.scan

1pub const scan = @import("scan.zig");

1//! Byte level CSS scanning shared by the sheet parser and the media reader.2//!3//! These helpers respect strings, comments, and bracket nesting, which is what4//! keeps a declaration delimiter inside a data URL or a comma inside a media5//! query from ending the construct that holds it.67const std = @import("std");89pub fn findTopLevelByte(source: []const u8, start: usize, needle: u8) ?usize {10    var index = start;11    var square_depth: usize = 0;12    var paren_depth: usize = 0;13    while (index < source.len) : (index += 1) {14        const byte = source[index];15        if (byte == '"' or byte == '\'') {16            index = skipString(source, index);17            continue;18        }19        switch (byte) {20            '[' => square_depth += 1,21            ']' => {22                if (square_depth > 0) square_depth -= 1;23            },24            '(' => paren_depth += 1,25            ')' => {26                if (paren_depth > 0) paren_depth -= 1;27            },28            else => {},29        }30        if (byte == needle and square_depth == 0 and paren_depth == 0) return index;31    }32    return null;33}3435pub fn findBlockEnd(source: []const u8, open: usize) ?usize {36    var index = open + 1;37    var depth: usize = 1;38    while (index < source.len) : (index += 1) {39        const byte = source[index];40        if (byte == '"' or byte == '\'') {41            index = skipString(source, index);42            continue;43        }44        if (byte == '/' and index + 1 < source.len and source[index + 1] == '*') {45            const end = std.mem.indexOf(u8, source[index + 2 ..], "*/") orelse return null;46            index += end + 3;47            continue;48        }49        if (byte == '{') {50            depth += 1;51            continue;52        }53        if (byte == '}') {54            depth -= 1;55            if (depth == 0) return index;56        }57    }58    return null;59}6061pub fn skipString(source: []const u8, quote: usize) usize {62    var index = quote + 1;63    while (index < source.len) : (index += 1) {64        if (source[index] == '\\') {65            if (index + 1 < source.len) index += 1;66            continue;67        }68        if (source[index] == source[quote]) return index;69    }70    return source.len;71}7273pub fn findDeclarationEnd(source: []const u8, start: usize) usize {74    return findTopLevelByte(source, start, ';') orelse source.len;75}7677pub fn findParenEnd(source: []const u8, open: usize) ?usize {78    var index = open + 1;79    var depth: usize = 1;80    while (index < source.len) : (index += 1) {81        const byte = source[index];82        if (byte == '"' or byte == '\'') {83            index = skipString(source, index);84            continue;85        }86        if (byte == '/' and index + 1 < source.len and source[index + 1] == '*') {87            const end = std.mem.indexOf(u8, source[index + 2 ..], "*/") orelse return null;88            index += end + 3;89            continue;90        }91        if (byte == '(') {92            depth += 1;93            continue;94        }95        if (byte == ')') {96            depth -= 1;97            if (depth == 0) return index;98        }99    }100    return null;101}102103pub fn containsTopLevelLogical(source: []const u8) bool {104    var index: usize = 0;105    var paren_depth: usize = 0;106    while (index < source.len) : (index += 1) {107        const byte = source[index];108        if (byte == '"' or byte == '\'') {109            index = skipString(source, index);110            continue;111        }112        switch (byte) {113            '(' => paren_depth += 1,114            ')' => {115                if (paren_depth > 0) paren_depth -= 1;116            },117            else => {},118        }119        if (paren_depth == 0 and identByte(byte)) {120            const end = readIdent(source, index);121            const word = source[index..end];122            if (std.ascii.eqlIgnoreCase(word, "and") or std.ascii.eqlIgnoreCase(word, "or")) return true;123            index = end - 1;124        }125    }126    return false;127}128129pub fn consumePrefixIgnoreCase(source: []const u8, prefix: []const u8) ?[]const u8 {130    if (source.len < prefix.len) return null;131    if (!std.ascii.eqlIgnoreCase(source[0..prefix.len], prefix)) return null;132    return source[prefix.len..];133}134135pub fn endsWithIgnoreCase(source: []const u8, suffix: []const u8) bool {136    if (source.len < suffix.len) return false;137    return std.ascii.eqlIgnoreCase(source[source.len - suffix.len ..], suffix);138}139140pub fn consumeWord(source: []const u8, index: *usize, word: []const u8) bool {141    index.* = skipCssSpace(source, index.*);142    const end = readIdent(source, index.*);143    if (end == index.* or !std.ascii.eqlIgnoreCase(source[index.*..end], word)) return false;144    index.* = end;145    return true;146}147148pub fn skipCssSpace(source: []const u8, start: usize) usize {149    var index = start;150    while (index < source.len and std.ascii.isWhitespace(source[index])) index += 1;151    return index;152}153154pub fn readIdent(source: []const u8, start: usize) usize {155    var index = start;156    while (index < source.len and identByte(source[index])) index += 1;157    return index;158}159160pub fn identByte(byte: u8) bool {161    return std.ascii.isAlphanumeric(byte) or byte == '_' or byte == '-';162}163164pub fn skipSpaceAndComments(source: []const u8, start: usize) usize {165    var index = start;166    while (index < source.len) {167        while (index < source.len and std.ascii.isWhitespace(source[index])) index += 1;168        if (index + 1 < source.len and source[index] == '/' and source[index + 1] == '*') {169            const end = std.mem.indexOf(u8, source[index + 2 ..], "*/") orelse return source.len;170            index += end + 4;171            continue;172        }173        return index;174    }175    return index;176}177178pub const AtRuleBoundaryKind = enum {179    semicolon,180    block,181};182183pub const AtRuleBoundary = struct {184    kind: AtRuleBoundaryKind,185    index: usize,186};187188pub fn findAtRuleBoundary(source: []const u8, start: usize) ?AtRuleBoundary {189    var index = start;190    var square_depth: usize = 0;191    var paren_depth: usize = 0;192    while (index < source.len) : (index += 1) {193        const byte = source[index];194        if (byte == '"' or byte == '\'') {195            index = skipString(source, index);196            continue;197        }198        switch (byte) {199            '[' => square_depth += 1,200            ']' => {201                if (square_depth > 0) square_depth -= 1;202            },203            '(' => paren_depth += 1,204            ')' => {205                if (paren_depth > 0) paren_depth -= 1;206            },207            ';' => if (square_depth == 0 and paren_depth == 0) return .{ .kind = .semicolon, .index = index },208            '{' => if (square_depth == 0 and paren_depth == 0) return .{ .kind = .block, .index = index },209            else => {},210        }211    }212    return null;213}