Adding support for comments with "//" (#3)

* support comments

* adding changelog

* correct tests

* comparison with starrit0

* merge branch with starrit0

CHANGELOG.md

@@ -1,6 +1,13 @@
+v1.10.0 [2020-05-22]
+-------------------
+
+#### New features
+- Adding support for inline comments with '//' 
+
+
 v1.9.0 [2020-05-12]
 -------------------
 
 #### New features
-Adding support for all bitwise operators
-Replacing all operators by constants for potential future changes
+- Adding support for all bitwise operators
+- Replacing all operators by constants for potential future changes

constants/constants.go

@@ -25,20 +25,18 @@ const (
 	OpEndsWith       = "endsWith"
 	OpMatches        = "matches"
 	OpRange          = ".."
+	OpBitwiseAnd     = "&"
+	OpBitwiseOr      = "|"
+	OpBitwiseXor     = "^"
+	OpBitwiseLShift  = "<<"
+	OpBitwiseRShift  = ">>"
 
 	// Unary Nodes Operators
 	OpPositive   = "+"
 	OpNegative   = "-"
 	OpNotSymbol  = "!"
 	OpNotVerbose = "not"
-
-	// Bitwise Operators
-	OpBitwiseNot    = "~"
-	OpBitwiseAnd    = "&"
-	OpBitwiseOr     = "|"
-	OpBitwiseXor    = "^"
-	OpBitwiseLShift = "<<"
-	OpBitwiseRShift = ">>"
+	OpBitwiseNot = "~"
 
 	SingleOperators       = "+-/%#,?:~^"
 	DoubleFirstOperators  = "&|=*<>!"

expr_test.go

@@ -3,14 +3,15 @@ package expr_test
 import (
 	"encoding/json"
 	"fmt"
-	"github.com/metronlab/expr/ast"
-	"github.com/metronlab/expr/constants"
-	"github.com/metronlab/expr/file"
 	"reflect"
 	"strings"
 	"testing"
 	"time"
 
+	"github.com/metronlab/expr/ast"
+	"github.com/metronlab/expr/constants"
+	"github.com/metronlab/expr/file"
+
 	"github.com/metronlab/expr"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -996,6 +997,23 @@ func TestExpr(t *testing.T) {
 			"27-2" + constants.OpBitwiseRShift + "(+4-3)+-2",
 			24,
 		},
+		// Comments
+		{
+			`	// 1 + 1
+					9 + 5 // 1 + 1
+					// 1 + 1
+					//another comment`,
+			14,
+		},
+		{
+			`	1 + // 1 + 1
+					9 + 5 // 1 + 1`,
+			15,
+		},
+		{
+			`	1 + 1 //1 + 2//`,
+			2,
+		},
 	}
 
 	for _, tt := range tests {
@@ -1026,6 +1044,30 @@ func TestExpr(t *testing.T) {
 	}
 }
 
+func TestComments_errors(t *testing.T) {
+	_, err := expr.Compile(
+		`# 2 + 2`,
+	)
+	assert.Error(t, err)
+	_, err = expr.Compile(
+		`	// 2 + 2
+				// 1 + 1`,
+	)
+	assert.Error(t, err)
+	_, err = expr.Compile(
+		"//",
+	)
+	assert.Error(t, err)
+	_, err = expr.Compile(
+		"//1 + 2 comment",
+	)
+	assert.Error(t, err)
+	_, err = expr.Compile(
+		"//1 + 2 \n//comment\n //3+4",
+	)
+	assert.Error(t, err)
+}
+
 func TestExpr_eval_with_env(t *testing.T) {
 	_, err := expr.Eval("true", expr.Env(map[string]interface{}{}))
 	assert.Error(t, err)

parser/lexer/lexer.go

@@ -99,6 +99,16 @@ func (l *lexer) word() string {
 	return l.input[l.start:l.end]
 }
 
+func (l *lexer) skipComment(r rune) stateFn {
+	for l.next() != eof && l.loc.Column != 0 {
+	}
+	if r == eof {
+		l.emitEOF()
+		return nil
+	}
+	return root
+}
+
 func (l *lexer) ignore() {
 	l.start = l.end
 	l.startLoc = l.loc

parser/lexer/state.go

@@ -1,8 +1,9 @@
 package lexer
 
 import (
-	"github.com/metronlab/expr/constants"
 	"strings"
+
+	"github.com/metronlab/expr/constants"
 )
 
 type stateFn func(*lexer) stateFn
@@ -12,6 +13,8 @@ func root(l *lexer) stateFn {
 	case r == eof:
 		l.emitEOF()
 		return nil
+	case IsComment(r, l):
+		return l.skipComment(r)
 	case IsSpace(r):
 		l.ignore()
 		return root

parser/lexer/utils.go

@@ -7,6 +7,13 @@ import (
 	"unicode/utf8"
 )
 
+func IsComment(r rune, l *lexer) bool {
+	if l.end >= len(l.input) {
+		return false
+	}
+	return l.input[l.end-1] == '/' && l.input[l.end] == '/'
+}
+
 func IsSpace(r rune) bool {
 	return unicode.IsSpace(r)
 }