Add tests of compiler/parser package

3 files changed, 13 insertions, 4 deletions

diff --git a/compiler/parser/error.go b/compiler/parser/error.go
index 8be6600..be81da4 100644
--- a/compiler/parser/error.go
+++ b/compiler/parser/error.go
@@ -15,6 +15,7 @@ var (
 	// syntax errors
 	synErrUnexpectedToken        = fmt.Errorf("unexpected token")
 	synErrNullPattern            = fmt.Errorf("a pattern must be a non-empty byte sequence")
+	synErrUnmatchablePattern     = fmt.Errorf("a pattern cannot match any characters")
 	synErrAltLackOfOperand       = fmt.Errorf("an alternation expression must have operands")
 	synErrRepNoTarget            = fmt.Errorf("a repeat expression must have an operand")
 	synErrGroupNoElem            = fmt.Errorf("a grouping expression must include at least one character")
diff --git a/compiler/parser/parser.go b/compiler/parser/parser.go
index 70d1ce6..fd85fab 100644
--- a/compiler/parser/parser.go
+++ b/compiler/parser/parser.go
@@ -205,7 +205,7 @@ func (p *parser) parseSingleChar() CPTree {
 		}
 		inverse := exclude(elem, genAnyCharAST())
 		if inverse == nil {
-			panic(fmt.Errorf("a pattern that isn't matching any symbols"))
+			p.raiseParseError(synErrUnmatchablePattern, "")
 		}
 		for {
 			elem := p.parseBExpElem()
@@ -214,7 +214,7 @@ func (p *parser) parseSingleChar() CPTree {
 			}
 			inverse = exclude(elem, inverse)
 			if inverse == nil {
-				panic(fmt.Errorf("a pattern that isn't matching any symbols"))
+				p.raiseParseError(synErrUnmatchablePattern, "")
 			}
 		}
 		if p.consume(tokenKindEOF) {
@@ -355,12 +355,12 @@ func (p *parser) parseCharProp() CPTree {
 			r := cpRanges[0]
 			alt = exclude(newRangeSymbolNode(r.From, r.To), genAnyCharAST())
 			if alt == nil {
-				panic(fmt.Errorf("a pattern that isn't matching any symbols"))
+				p.raiseParseError(synErrUnmatchablePattern, "")
 			}
 			for _, r := range cpRanges[1:] {
 				alt = exclude(newRangeSymbolNode(r.From, r.To), alt)
 				if alt == nil {
-					panic(fmt.Errorf("a pattern that isn't matching any symbols"))
+					p.raiseParseError(synErrUnmatchablePattern, "")
 				}
 			}
 		} else {
diff --git a/compiler/parser/parser_test.go b/compiler/parser/parser_test.go
index 1fa0489..bad6404 100644
--- a/compiler/parser/parser_test.go
+++ b/compiler/parser/parser_test.go
@@ -472,6 +472,14 @@ func TestParse(t *testing.T) {
 			syntaxError: synErrRangePropIsUnavailable,
 		},
 		{
+			pattern:     "[^\\u{0000}-\\u{10FFFF}]",
+			syntaxError: synErrUnmatchablePattern,
+		},
+		{
+			pattern:     "[^\\u{0000}-\\u{FFFF}\\u{010000}-\\u{10FFFF}]",
+			syntaxError: synErrUnmatchablePattern,
+		},
+		{
 			pattern: "[^]",
 			ast:     newSymbolNode('^'),
 		},