feat: improve regex analysers in XML (#831)

lexer.go

@@ -60,15 +60,23 @@ type Config struct {
 
 	// Analyse is a list of regexes to match against the input.
 	//
-	// The sum of all the score of matching patterns will be
+	// If a match is found, the score is returned if single attribute is set to true,
+	// otherwise the sum of all the score of matching patterns will be
 	// used as the final score.
-	Analyse []AnalyseConfig `xml:"analyse,omitempty"`
+	Analyse *AnalyseConfig `xml:"analyse,omitempty"`
 }
 
-// AnalyseConfig defines a single regex analyser pattern.
+// AnalyseConfig defines the list of regexes analysers.
 type AnalyseConfig struct {
-	Regex string  `xml:"regex,attr"`
-	Score float32 `xml:"score,attr"`
+	Regexes []RegexConfig `xml:"regex,omitempty"`
+	// If true, the score is returned despite other matches.
+	Single bool `xml:"single,attr"`
+}
+
+// RegexConfig defines a single regex pattern and its score in case of match.
+type RegexConfig struct {
+	Pattern string  `xml:"pattern,attr"`
+	Score   float32 `xml:"score,attr"`
 }
 
 // Token output to formatter.

lexers/embedded/c++.xml

@@ -19,8 +19,10 @@
     <mime_type>text/x-c++hdr</mime_type>
     <mime_type>text/x-c++src</mime_type>
     <ensure_nl>true</ensure_nl>
-    <analyse regex="#include &lt;[a-z_]+>" score="0.2" />
-    <analyse regex="using namespace " score="0.4" />
+    <analyse single="true">
+      <regex pattern="#include &lt;[a-z_]+>" score="0.2" />
+      <regex pattern="using namespace " score="0.4" />
+    </analyse>
   </config>
   <rules>
     <state name="classname">

lexers/embedded/c.xml

@@ -11,8 +11,10 @@
     <mime_type>image/x-xbitmap</mime_type>
     <mime_type>image/x-xpixmap</mime_type>
     <ensure_nl>true</ensure_nl>
-    <analyse regex="(?m)^\s*#include &lt;" score="0.1"/>
-    <analyse regex="(?m)^\s*#ifn?def " score="0.1" />
+    <analyse single="true" >
+      <regex pattern="(?m)^\s*#include &lt;" score="0.1" />
+      <regex pattern="(?m)^\s*#ifn?def " score="0.1" />
+    </analyse>
   </config>
   <rules>
     <state name="statement">

regexp.go

@@ -298,11 +298,12 @@ func (r *RegexLexer) SetAnalyser(analyser func(text string) float32) Lexer {
 	return r
 }
 
-func (r *RegexLexer) AnalyseText(text string) float32 { // nolint
+// AnalyseText scores how likely a fragment of text is to match this lexer, between 0.0 and 1.0.
+func (r *RegexLexer) AnalyseText(text string) float32 {
 	if r.analyser != nil {
 		return r.analyser(text)
 	}
-	return 0.0
+	return 0
 }
 
 // SetConfig replaces the Config for this Lexer.
@@ -311,7 +312,8 @@ func (r *RegexLexer) SetConfig(config *Config) *RegexLexer {
 	return r
 }
 
-func (r *RegexLexer) Config() *Config { // nolint
+// Config returns the Config for this Lexer.
+func (r *RegexLexer) Config() *Config {
 	return r.config
 }
 
@@ -406,7 +408,8 @@ func (r *RegexLexer) needRules() error {
 	return err
 }
 
-func (r *RegexLexer) Tokenise(options *TokeniseOptions, text string) (Iterator, error) { // nolint
+// Tokenise text using lexer, returning an iterator.
+func (r *RegexLexer) Tokenise(options *TokeniseOptions, text string) (Iterator, error) {
 	err := r.needRules()
 	if err != nil {
 		return nil, err

serialise.go

@@ -131,35 +131,58 @@ func NewXMLLexer(from fs.FS, path string) (*RegexLexer, error) {
 	if err != nil {
 		return nil, err
 	}
+
 	for _, glob := range append(config.Filenames, config.AliasFilenames...) {
 		_, err := filepath.Match(glob, "")
 		if err != nil {
 			return nil, fmt.Errorf("%s: %q is not a valid glob: %w", config.Name, glob, err)
 		}
 	}
-	type regexAnalyse struct {
-		re    *regexp2.Regexp
-		score float32
-	}
-	regexAnalysers := make([]regexAnalyse, 0, len(config.Analyse))
-	for _, ra := range config.Analyse {
-		re, err := regexp2.Compile(ra.Regex, regexp2.None)
-		if err != nil {
-			return nil, fmt.Errorf("%s: %q is not a valid analyser regex: %w", config.Name, ra.Regex, err)
+
+	var analyserFn func(string) float32
+
+	if config.Analyse != nil {
+		type regexAnalyse struct {
+			re    *regexp2.Regexp
+			score float32
 		}
-		regexAnalysers = append(regexAnalysers, regexAnalyse{re, ra.Score})
-	}
-	return &RegexLexer{
-		config: config,
-		analyser: func(text string) float32 {
+
+		regexAnalysers := make([]regexAnalyse, 0, len(config.Analyse.Regexes))
+
+		for _, ra := range config.Analyse.Regexes {
+			re, err := regexp2.Compile(ra.Pattern, regexp2.None)
+			if err != nil {
+				return nil, fmt.Errorf("%s: %q is not a valid analyser regex: %w", config.Name, ra.Pattern, err)
+			}
+
+			regexAnalysers = append(regexAnalysers, regexAnalyse{re, ra.Score})
+		}
+
+		analyserFn = func(text string) float32 {
 			var score float32
+
 			for _, ra := range regexAnalysers {
-				if ok, _ := ra.re.MatchString(text); ok {
+				ok, err := ra.re.MatchString(text)
+				if err != nil {
+					return 0
+				}
+
+				if ok && config.Analyse.Single {
+					return ra.score
+				}
+
+				if ok {
 					score += ra.score
 				}
 			}
+
 			return score
-		},
+		}
+	}
+
+	return &RegexLexer{
+		config:   config,
+		analyser: analyserFn,
 		fetchRulesFunc: func() (Rules, error) {
 			var lexer struct {
 				Config