Improved tokenizer performance

src/build/token/Keywords.go

@@ -1,9 +0,0 @@
-package token
-
-// Keywords is a map of all keywords used in the language.
-var Keywords = map[string]Kind{
-	"if":     If,
-	"import": Import,
-	"loop":   Loop,
-	"return": Return,
-}

src/build/token/Tokenize.go

@@ -1,5 +1,7 @@
 package token
 
+import "bytes"
+
 // Tokenize turns the file contents into a list of tokens.
 func Tokenize(buffer []byte) List {
 	var (
@@ -84,10 +86,25 @@ func Tokenize(buffer []byte) List {
 
 				identifier := buffer[position:i]
 				kind := Identifier
-				keyword, isKeyword := Keywords[string(identifier)]
 
-				if isKeyword {
+				switch identifier[0] {
-					kind = keyword
+				case 'i':
+					switch {
+					case bytes.Equal(identifier, []byte("if")):
+						kind = If
+					case bytes.Equal(identifier, []byte("import")):
+						kind = Import
+					}
+				case 'l':
+					switch {
+					case bytes.Equal(identifier, []byte("loop")):
+						kind = Loop
+					}
+				case 'r':
+					switch {
+					case bytes.Equal(identifier, []byte("return")):
+						kind = Return
+					}
 				}
 
 				tokens = append(tokens, Token{Kind: kind, Position: position, Length: Length(len(identifier))})