fix double escapes

pql/parser_test.go

@@ -75,7 +75,7 @@ func TestParser_Parse(t *testing.T) {
 
 	// Parse with only arguments.
 	t.Run("ArgumentsOnly", func(t *testing.T) {
-		q, err := pql.ParseString(`MyCall( key= value, foo='bar', age = 12 , bool0=true, bool1=false, x=null, escape="\" \\escape\n"  )`)
+		q, err := pql.ParseString(`MyCall( key= value, foo='bar', age = 12 , bool0=true, bool1=false, x=null, escape="\" \\escape\n\\\\"  )`)
 		if err != nil {
 			t.Fatal(err)
 		} else if !reflect.DeepEqual(q.Calls[0],
@@ -88,7 +88,7 @@ func TestParser_Parse(t *testing.T) {
 					"bool0":  true,
 					"bool1":  false,
 					"x":      nil,
-					"escape": "\" \\escape\n",
+					"escape": "\" \\escape\n\\\\",
 				},
 			},
 		) {

pql/pql.peg

@@ -49,8 +49,8 @@ item <- ( 'null' &(comma / sp close) { p.addVal(nil) }
          / '\'' < singlequotedstring > '\'' { p.addVal(buffer[begin:end]) }
          )
 
-doublequotedstring <- ( '\\\"' / [^"] )*
-singlequotedstring <- ( '\\\'' / [^'] )*
+doublequotedstring <- ( '\\"' / '\\\\' / [^"] )*
+singlequotedstring <- ( '\\\'' / '\\\\' / [^'] )*
 
 fieldExpr <- [[A-Z]] ( [[A-Z]] / [0-9] / '_' / '-' )*
 field <- <fieldExpr / reserved> { p.addField(buffer[begin:end]) }