docs: note about Get() being slow due to file matching

alecthomas · alecthomas · commit 9087c632c4d4 · 2023-09-22T07:00:14.000+10:00
Fixes #714
diff --git a/lexers/lexers.go b/lexers/lexers.go
@@ -30,6 +30,9 @@ func Names(withAliases bool) []string {
 }
 
 // Get a Lexer by name, alias or file extension.
+//
+// Note that this if there isn't an exact match on name or alias, this will
+// call Match(), so it is not efficient.
 func Get(name string) chroma.Lexer {
 	return GlobalLexerRegistry.Get(name)
 }
@@ -40,6 +43,9 @@ func MatchMimeType(mimeType string) chroma.Lexer {
 }
 
 // Match returns the first lexer matching filename.
+//
+// Note that this iterates over all file patterns in all lexers, so it's not
+// particularly efficient.
 func Match(filename string) chroma.Lexer {
 	return GlobalLexerRegistry.Match(filename)
 }
diff --git a/lexers/lexers_test.go b/lexers/lexers_test.go
@@ -179,7 +179,6 @@ func FileTestAnalysis(t *testing.T, lexer chroma.Lexer, actualFilepath, expected
 				assert.NoError(t, err)
 				assert.NoError(t, f.Close())
 			} else {
-				// fail via an assertion of string comparison for nicer diff output
 				assert.Equal(t, string(expectedData), actualData.String())
 			}
 		}
diff --git a/registry.go b/registry.go
@@ -97,6 +97,8 @@ func (l *LexerRegistry) MatchMimeType(mimeType string) Lexer {
 }
 
 // Match returns the first lexer matching filename.
+//
+// Note that this iterates over all file patterns in all lexers, so is not fast.
 func (l *LexerRegistry) Match(filename string) Lexer {
 	filename = filepath.Base(filename)
 	matched := PrioritisedLexers{}

Original file line number	Diff line number	Diff line change
`@@ -30,6 +30,9 @@ func Names(withAliases bool) []string {`
`30`	`30`	`}`
`31`	`31`
`32`	`32`	`// Get a Lexer by name, alias or file extension.`
	`33`	`+//`
	`34`	`+// Note that this if there isn't an exact match on name or alias, this will`
	`35`	`+// call Match(), so it is not efficient.`
`33`	`36`	`func Get(name string) chroma.Lexer {`
`34`	`37`	`return GlobalLexerRegistry.Get(name)`
`35`	`38`	`}`
`@@ -40,6 +43,9 @@ func MatchMimeType(mimeType string) chroma.Lexer {`
`40`	`43`	`}`
`41`	`44`
`42`	`45`	`// Match returns the first lexer matching filename.`
	`46`	`+//`
	`47`	`+// Note that this iterates over all file patterns in all lexers, so it's not`
	`48`	`+// particularly efficient.`
`43`	`49`	`func Match(filename string) chroma.Lexer {`
`44`	`50`	`return GlobalLexerRegistry.Match(filename)`
`45`	`51`	`}`
Original file line number	Diff line number	Diff line change
`@@ -179,7 +179,6 @@ func FileTestAnalysis(t *testing.T, lexer chroma.Lexer, actualFilepath, expected`
`179`	`179`	`assert.NoError(t, err)`
`180`	`180`	`assert.NoError(t, f.Close())`
`181`	`181`	`} else {`
`182`		`- // fail via an assertion of string comparison for nicer diff output`
`183`	`182`	`assert.Equal(t, string(expectedData), actualData.String())`
`184`	`183`	`}`
`185`	`184`	`}`
Original file line number	Diff line number	Diff line change
`@@ -97,6 +97,8 @@ func (l *LexerRegistry) MatchMimeType(mimeType string) Lexer {`
`97`	`97`	`}`
`98`	`98`
`99`	`99`	`// Match returns the first lexer matching filename.`
	`100`	`+//`
	`101`	`+// Note that this iterates over all file patterns in all lexers, so is not fast.`
`100`	`102`	`func (l *LexerRegistry) Match(filename string) Lexer {`
`101`	`103`	`filename = filepath.Base(filename)`
`102`	`104`	`matched := PrioritisedLexers{}`