Issue #15.

src/tokenizer/tokenizer.go

@@ -0,0 +1,202 @@
+package tokenizer
+
+import (
+	"strings"
+)
+
+type Token struct {
+	Token string
+}
+
+var delimiter = []byte{
+	'=',
+	';',
+	'{',
+	'}',
+	'(',
+	')',
+	'[',
+	']',
+	'<',
+	'>',
+	'!',
+	',',
+	':',
+	'&',
+	'|',
+	'+',
+	'-',
+	'*',
+	'/'} // TODO: modulo?
+
+var keywords = []string{
+	"var",
+	"if",
+	"while",
+	"switch",
+	"for",
+	"foreach",
+	"func",
+	"true",
+	"false",
+	"case",
+	"default",
+	"return",
+	"try",
+	"catch",
+	"exitwith",
+	"waituntil",
+	"code"}
+
+var whitespace = []byte{' ', '\n', '\t', '\r'}
+var identifier = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_"
+
+// Tokenizes the given byte array into syntax tokens,
+// which can be parsed later.
+func Tokenize(code []byte) []Token {
+	code = removeComments(code)
+	tokens := make([]Token, 0)
+	token, mask, isstring := "", false, false
+
+	for i := range code {
+		c := code[i]
+
+		// string masks (backslash)
+		if c == '\\' && !mask {
+			token += "\\"
+			mask = true
+			continue
+		}
+
+		// string
+		if c == '"' && !mask {
+			token += "\""
+			isstring = !isstring
+			continue
+		}
+
+		if isstring {
+			token += string(c)
+		} else {
+			// delimeter, keyword or variable/expression
+			if byteArrayContains(delimiter, c) {
+				if token != "" {
+					tokens = append(tokens, Token{token})
+				}
+
+				tokens = append(tokens, Token{string(c)})
+				token = ""
+			} else if stringArrayContains(strings.ToLower(token)) && !isIdentifierCharacter(c) {
+				tokens = append(tokens, Token{token})
+				token = ""
+			} else if !byteArrayContains(whitespace, c) {
+				token += string(c)
+			}
+		}
+
+		mask = false
+	}
+
+	return tokens
+}
+
+// Removes all comments from input byte array.
+// Comments are single line comments, starting with // (two slashes),
+// multi line comments with /* ... */ (slash star, star slash).
+func removeComments(code []byte) []byte {
+	newcode := make([]byte, len(code))
+	j, mask, isstring := 0, false, false
+
+	for i := 0; i < len(code); i++ {
+		c := code[i]
+
+		// do not remove comments from strings
+		if c == '\\' && !mask {
+			mask = true
+		}
+
+		if c == '"' && !mask {
+			isstring = !isstring
+		}
+
+		// single/multi line comment
+		if !isstring {
+			if c == '/' && nextChar(code, i) == '/' {
+				i = skipSingleLineComment(code, i+1)
+				continue
+			} else if c == '/' && nextChar(code, i) == '*' {
+				i = skipMultiLineComment(code, i+1)
+				continue
+			}
+		}
+
+		newcode[j] = c
+		j++
+		mask = false
+	}
+
+	return newcode[:j]
+}
+
+// Returns the next character in code starting at i.
+// If no character is left, '0' will be returned.
+func nextChar(code []byte, i int) byte {
+	i++
+
+	if i < len(code) {
+		return code[i]
+	}
+
+	return '0'
+}
+
+// Used to skip a line if a single line comment was found.
+func skipSingleLineComment(code []byte, i int) int {
+	for i < len(code) && code[i] != '\n' {
+		i++
+	}
+
+	return i
+}
+
+// Used to skip a block of characters if a multi line comment was found
+func skipMultiLineComment(code []byte, i int) int {
+	for i < len(code) && !(code[i] == '*' && nextChar(code, i) == '/') {
+		i++
+	}
+
+	return i + 1
+}
+
+// Checks if a byte array (string) contains a delimeter.
+func byteArrayContains(haystack []byte, needle byte) bool {
+	for i := range haystack {
+		if haystack[i] == needle {
+			return true
+		}
+	}
+
+	return false
+}
+
+// Checks if a byte array (string) contains a string delimeter.
+func stringArrayContains(needle string) bool {
+	for i := range keywords {
+		if keywords[i] == needle {
+			return true
+		}
+	}
+
+	return false
+}
+
+// Checks if a character is allowed for identifiers.
+func isIdentifierCharacter(c byte) bool {
+	for i := range identifier {
+		if identifier[i] == c {
+			return true
+		}
+	}
+
+	return false
+}