From 2c7fd79cfc5b1279d6bf0f8265d9741b3ae4d6e7 Mon Sep 17 00:00:00 2001
From: Steve Kemp <steve@steve.org.uk>
Date: Mon, 23 Dec 2019 19:39:26 +0200
Subject: [PATCH] Be less strict about identifier names.

This PR closes #58 by allowing digits in identifiers.  This might
cause surprises.
---
 lexer/lexer.go      | 43 +++++++------------------------------------
 lexer/lexer_test.go |  8 +++-----
 2 files changed, 10 insertions(+), 41 deletions(-)

diff --git a/lexer/lexer.go b/lexer/lexer.go
index b2be721..201c513 100644
--- a/lexer/lexer.go
+++ b/lexer/lexer.go
@@ -3,6 +3,7 @@ package lexer
 import (
 	"fmt"
 	"strings"
+	"unicode"
 
 	"github.com/skx/monkey/token"
 )
@@ -604,7 +605,12 @@ func (l *Lexer) peekChar() rune {
 
 // determinate ch is identifier or not
 func isIdentifier(ch rune) bool {
-	return !isDigit(ch) && !isWhitespace(ch) && !isBrace(ch) && !isOperator(ch) && !isComparison(ch) && !isCompound(ch) && !isBrace(ch) && !isParen(ch) && !isBracket(ch) && !isEmpty(ch)
+
+	if unicode.IsLetter(ch) || unicode.IsDigit(ch) || ch == '.' || ch == '?' || ch == '_' {
+		return true
+	}
+
+	return false
 }
 
 // is white space
@@ -612,41 +618,6 @@ func isWhitespace(ch rune) bool {
 	return ch == rune(' ') || ch == rune('\t') || ch == rune('\n') || ch == rune('\r')
 }
 
-// is operators
-func isOperator(ch rune) bool {
-	return ch == rune('+') || ch == rune('%') || ch == rune('-') || ch == rune('/') || ch == rune('*')
-}
-
-// is comparison
-func isComparison(ch rune) bool {
-	return ch == rune('=') || ch == rune('!') || ch == rune('>') || ch == rune('<')
-}
-
-// is compound
-func isCompound(ch rune) bool {
-	return ch == rune(',') || ch == rune(':') || ch == rune('"') || ch == rune(';')
-}
-
-// is brace
-func isBrace(ch rune) bool {
-	return ch == rune('{') || ch == rune('}')
-}
-
-// is bracket
-func isBracket(ch rune) bool {
-	return ch == rune('[') || ch == rune(']')
-}
-
-// is parenthesis
-func isParen(ch rune) bool {
-	return ch == rune('(') || ch == rune(')')
-}
-
-// is empty
-func isEmpty(ch rune) bool {
-	return rune(0) == ch
-}
-
 // is Digit
 func isDigit(ch rune) bool {
 	return rune('0') <= ch && ch <= rune('9')
diff --git a/lexer/lexer_test.go b/lexer/lexer_test.go
index a50fbdc..185b747 100644
--- a/lexer/lexer_test.go
+++ b/lexer/lexer_test.go
@@ -359,15 +359,13 @@ let a = "steve\t";
 let a = "steve\r";
 let a = "steve\\";
 let a = "steve\"";
-let c = 3.113£;
-.;
-`
-	input += "`/bin/ls`"
-	input += "/*\n"
+let c = 3.113;
+.;`
 
 	l := New(input)
 	tok := l.NextToken()
 	for tok.Type != token.EOF {
+
 		tok = l.NextToken()
 	}
 }