token: add token representations

parser/token.go

@@ -1,5 +1,7 @@
 package parser
 
+import "strconv"
+
 // Token is the set of lexical tokens of the HCL (HashiCorp Configuration Language)
 type Token int
 
@@ -36,6 +38,51 @@ const (
 	operator_end
 )
 
+var tokens = [...]string{
+	ILLEGAL: "ILLEGAL",
+
+	EOF:     "EOF",
+	COMMENT: "COMMENT",
+	NEWLINE: "NEWLINE",
+
+	IDENT:  "IDENT",
+	NUMBER: "NUMBER",
+	FLOAT:  "FLOAT",
+	BOOL:   "BOOL",
+	STRING: "STRING",
+
+	LBRACK: "[",
+	LBRACE: "{",
+	COMMA:  ",",
+	PERIOD: ".",
+
+	RBRACK: "]",
+	RBRACE: "}",
+
+	ASSIGN: "=",
+	ADD:    "+",
+	SUB:    "-",
+
+	EPLUS:  "e",
+	EMINUS: "e-",
+}
+
+// String returns the string corresponding to the token tok.
+// For operators, delimiters, and keywords the string is the actual
+// token character sequence (e.g., for the token ADD, the string is
+// "+"). For all other tokens the string corresponds to the token
+// constant name (e.g. for the token IDENT, the string is "IDENT").
+func (t Token) String() string {
+	s := ""
+	if 0 <= t && t < Token(len(tokens)) {
+		s = tokens[t]
+	}
+	if s == "" {
+		s = "token(" + strconv.Itoa(int(t)) + ")"
+	}
+	return s
+}
+
 // IsLiteral returns true for tokens corresponding to identifiers and basic
 // type literals; it returns false otherwise.
 func (t Token) IsLiteral() bool { return literal_beg < t && t < literal_end }