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Improve parser robustness and highlighting performance #23

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108 changes: 63 additions & 45 deletions lib/src/highlighter.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -39,7 +39,13 @@ class Highlighter {
required this.language,
required this.theme,
}) {
_grammar = _cache[language]!;
final grammar = _cache[language];
if (grammar == null) {
throw UnsupportedError(
'Language "$language" has not been initialized or added.',
);
}
_grammar = grammar;
}

/// Initializes the [Highlighter] with the given list of [languages]. This
Expand Down Expand Up @@ -118,39 +124,36 @@ class Highlighter {

(TextSpan, int) _formatBrackets(String text, int bracketCounter) {
var spans = <TextSpan>[];
var plainText = '';
for (var char in text.characters) {
if (_isStartingBracket(char)) {
if (plainText.isNotEmpty) {
spans.add(TextSpan(text: plainText));
plainText = '';
}
final plainText = StringBuffer();

void flushPlainText() {
if (plainText.isEmpty) return;
spans.add(TextSpan(text: plainText.toString()));
plainText.clear();
}

for (var i = 0; i < text.length; i += 1) {
final charCode = text.codeUnitAt(i);
final char = text[i];
if (_isStartingBracket(charCode)) {
flushPlainText();
spans.add(TextSpan(
text: char,
style: _getBracketStyle(bracketCounter),
));
bracketCounter += 1;
plainText = '';
} else if (_isEndingBracket(char)) {
if (plainText.isNotEmpty) {
spans.add(TextSpan(text: plainText));
plainText = '';
}

} else if (_isEndingBracket(charCode)) {
flushPlainText();
bracketCounter -= 1;
spans.add(TextSpan(
text: char,
style: _getBracketStyle(bracketCounter),
));
plainText = '';
} else {
plainText += char;
plainText.writeCharCode(charCode);
}
}
if (plainText.isNotEmpty) {
spans.add(TextSpan(text: plainText));
}
flushPlainText();

if (spans.length == 1) {
return (spans[0], bracketCounter);
Expand All @@ -166,12 +169,12 @@ class Highlighter {
return _bracketStyles[bracketCounter % _bracketStyles.length];
}

bool _isStartingBracket(String bracket) {
return bracket == '{' || bracket == '[' || bracket == '(';
bool _isStartingBracket(int charCode) {
return charCode == 0x7B || charCode == 0x5B || charCode == 0x28;
}

bool _isEndingBracket(String bracket) {
return bracket == '}' || bracket == ']' || bracket == ')';
bool _isEndingBracket(int charCode) {
return charCode == 0x7D || charCode == 0x5D || charCode == 0x29;
}
}

Expand All @@ -180,6 +183,7 @@ class HighlighterTheme {
final TextStyle _wrapper;
TextStyle? _fallback;
final _scopes = <String, TextStyle>{};
final _styleCache = <String, TextStyle?>{};

HighlighterTheme._({required TextStyle wrapper}) : _wrapper = wrapper;

Expand Down Expand Up @@ -287,14 +291,18 @@ class HighlighterTheme {

var fontStyleSetting = setting['fontStyle'];
if (fontStyleSetting is String) {
if (fontStyleSetting == 'italic') {
fontStyle = FontStyle.italic;
} else if (fontStyleSetting == 'bold') {
fontWeight = FontWeight.bold;
} else if (fontStyleSetting == 'underline') {
textDecoration = TextDecoration.underline;
} else {
throw Exception('WARNING unknown style: $fontStyleSetting');
final styles = fontStyleSetting.trim().split(RegExp(r'\s+'));
for (final style in styles) {
if (style.isEmpty) continue;
if (style == 'italic') {
fontStyle = FontStyle.italic;
} else if (style == 'bold') {
fontWeight = FontWeight.bold;
} else if (style == 'underline') {
textDecoration = TextDecoration.underline;
} else {
throw Exception('WARNING unknown style: $fontStyleSetting');
}
}
}

Expand All @@ -308,28 +316,38 @@ class HighlighterTheme {

void _addScope(String scope, TextStyle style) {
_scopes[scope] = style;
_styleCache.clear();
}

TextStyle? _getStyle(List<String> scope) {
for (var s in scope) {
var fallbacks = _fallbacks(s);
for (var f in fallbacks) {
var style = _scopes[f];
if (style != null) {
return style;
}
final style = _getStyleForScope(s);
if (style != null) {
return style;
}
}
return _fallback;
}

List<String> _fallbacks(String scope) {
var fallbacks = <String>[];
var parts = scope.split('.');
for (var i = 0; i < parts.length; i++) {
var s = parts.sublist(0, i + 1).join('.');
fallbacks.add(s);
TextStyle? _getStyleForScope(String scope) {
if (_styleCache.containsKey(scope)) {
return _styleCache[scope];
}

String candidate = scope;
while (candidate.isNotEmpty) {
final style = _scopes[candidate];
if (style != null) {
_styleCache[scope] = style;
return style;
}

final lastSeparator = candidate.lastIndexOf('.');
if (lastSeparator == -1) break;
candidate = candidate.substring(0, lastSeparator);
}
return fallbacks.reversed.toList();

_styleCache[scope] = null;
return null;
}
}
102 changes: 61 additions & 41 deletions lib/src/span_parser.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -236,14 +236,19 @@ abstract class GrammarMatcher {
final matchStartLocation = location;
if (captures != null) {
final match = scanner.substring(start, end);
var captureSearchOffset = 0;
for (int i = 0; i <= lastMatch.groupCount; ++i) {
// Skip if we don't have a scope or nested patterns for this capture.
if (!captures.containsKey(i.toString())) continue;

final captureText = lastMatch.group(i);
if (captureText == null || captureText.isEmpty) continue;

final startOffset = match.indexOf(captureText);
final startOffset = i == 0
? 0
: match.indexOf(captureText, captureSearchOffset);
if (startOffset < 0) continue;
captureSearchOffset = startOffset + captureText.length;
final capture = captures[i.toString()] as Map<String, Object?>;
final captureStartLocation = matchStartLocation.offset(startOffset);
final captureEndLocation =
Expand Down Expand Up @@ -272,11 +277,11 @@ abstract class GrammarMatcher {

/// A simple matcher which matches a single line.
class _SimpleMatcher extends GrammarMatcher {
_SimpleMatcher(Map<String, Object?> json)
_SimpleMatcher(super.json)
: match = RegExp(json['match'] as String, multiLine: true),
captures = (json['captures'] as Map<String, Object?>?)
?.cast<String, Map<String, Object?>>(),
super._(json);
super._();

static bool isType(Map<String, Object?> json) {
return json.containsKey('match');
Expand Down Expand Up @@ -309,7 +314,7 @@ class _SimpleMatcher extends GrammarMatcher {
}

class _MultilineMatcher extends GrammarMatcher {
_MultilineMatcher(Map<String, Object?> json)
_MultilineMatcher(super.json)
: begin = RegExp(json['begin'] as String, multiLine: true),
beginCaptures = json['beginCaptures'] as Map<String, Object?>?,
contentName = json['contentName'] as String?,
Expand All @@ -325,8 +330,9 @@ class _MultilineMatcher extends GrammarMatcher {
?.cast<Map<String, Object?>>()
.map((e) => GrammarMatcher.parse(e))
.toList()
.cast<GrammarMatcher>(),
super._(json);
.cast<GrammarMatcher>() ??
const <GrammarMatcher>[],
super._();

static bool isType(Map<String, Object?> json) {
return json.containsKey('begin') &&
Expand Down Expand Up @@ -374,7 +380,7 @@ class _MultilineMatcher extends GrammarMatcher {
/// be null if this property is provided.
final Map<String, Object?>? captures;

final List<GrammarMatcher>? patterns;
final List<GrammarMatcher> patterns;

void _scanBegin(Grammar grammar, LineScanner scanner, ScopeStack scopeStack) {
final location = scanner.location;
Expand All @@ -397,21 +403,14 @@ class _MultilineMatcher extends GrammarMatcher {
LineScanner scanner,
ScopeStack scopeStack,
) {
while (!scanner.isDone) {
if (String.fromCharCode(scanner.peekChar()!) == '\n') {
scanner.readChar();
break;
}
bool foundMatch = false;
for (final pattern in patterns ?? <GrammarMatcher>[]) {
if (pattern.scan(grammar, scanner, scopeStack)) {
foundMatch = true;
break;
}
}
if (!foundMatch) {
scanner.readChar();
}
_scanUntil(
grammar,
scanner,
scopeStack,
() => scanner.peekChar() == 0x0A,
);
if (!scanner.isDone) {
scanner.readChar();
}
}

Expand All @@ -420,21 +419,41 @@ class _MultilineMatcher extends GrammarMatcher {
LineScanner scanner,
ScopeStack scopeStack,
) {
while (!scanner.isDone && end != null && !scanner.matches(end!)) {
bool foundMatch = false;
for (final pattern in patterns ?? <GrammarMatcher>[]) {
if (pattern.scan(grammar, scanner, scopeStack)) {
foundMatch = true;
break;
}
}
if (!foundMatch) {
// Move forward by a character, try again.
if (end == null) return;
_scanUntil(
grammar,
scanner,
scopeStack,
() => scanner.matches(end!),
);
}

void _scanUntil(
Grammar grammar,
LineScanner scanner,
ScopeStack scopeStack,
bool Function() shouldStop,
) {
while (!scanner.isDone && !shouldStop()) {
if (!_scanPatterns(grammar, scanner, scopeStack)) {
scanner.readChar();
}
}
}

bool _scanPatterns(
Grammar grammar,
LineScanner scanner,
ScopeStack scopeStack,
) {
for (final pattern in patterns) {
if (pattern.scan(grammar, scanner, scopeStack)) {
return true;
}
}
return false;
}

void _scanEnd(Grammar grammar, LineScanner scanner, ScopeStack scopeStack) {
final location = scanner.location;
if (end != null && !scanner.scan(end!)) {
Expand Down Expand Up @@ -531,31 +550,32 @@ class _MultilineMatcher extends GrammarMatcher {
if (end != null) 'end': end!.pattern,
if (endCaptures != null) 'endCaptures': endCaptures,
if (whileCond != null) 'while': whileCond!.pattern,
if (patterns != null)
'patterns': patterns!.map((e) => e.toJson()).toList(),
if (patterns.isNotEmpty)
'patterns': patterns.map((e) => e.toJson()).toList(),
};
}
}

class _PatternMatcher extends GrammarMatcher {
_PatternMatcher(Map<String, Object?> json)
_PatternMatcher(super.json)
: patterns = (json['patterns'] as List<Object?>?)
?.cast<Map<String, Object?>>()
.map((e) => GrammarMatcher.parse(e))
.toList()
.cast<GrammarMatcher>(),
super._(json);
.cast<GrammarMatcher>() ??
const <GrammarMatcher>[],
super._();

static bool isType(Map<String, Object?> json) {
return json.containsKey('patterns');
}

final List<GrammarMatcher>? patterns;
final List<GrammarMatcher> patterns;

@override
bool scan(Grammar grammar, LineScanner scanner, ScopeStack scopeStack) {
// Try each rule in the include and return after the first successful match.
for (final pattern in patterns!) {
for (final pattern in patterns) {
if (pattern.scan(grammar, scanner, scopeStack)) {
return true;
}
Expand All @@ -567,8 +587,8 @@ class _PatternMatcher extends GrammarMatcher {
Map<String, Object?> toJson() {
return {
if (name != null) 'name': name,
if (patterns != null)
'patterns': patterns!.map((e) => e.toJson()).toList(),
if (patterns.isNotEmpty)
'patterns': patterns.map((e) => e.toJson()).toList(),
};
}
}
Expand Down
2 changes: 0 additions & 2 deletions lib/syntax_highlight.dart
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Original file line number Diff line number Diff line change
@@ -1,4 +1,2 @@
library syntax_highlight;

export 'src/highlighter.dart';
export 'src/code_editor.dart';
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