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|
package driver
import (
"fmt"
"strings"
"testing"
"github.com/nihei9/vartan/grammar"
"github.com/nihei9/vartan/spec"
)
func TestParserWithSyntaxErrors(t *testing.T) {
tests := []struct {
caption string
specSrc string
src string
synErrCount int
}{
{
caption: "the parser can report a syntax error",
specSrc: `
s
: foo
;
foo: 'foo';
`,
src: `bar`,
synErrCount: 1,
},
{
caption: "when the parser reduced a production having the reduce directive, the parser will recover from an error state",
specSrc: `
seq
: seq elem ';'
| elem ';'
| error ';' #recover
;
elem
: a b c
;
ws: "[\u{0009}\u{0020}]+" #skip;
a: 'a';
b: 'b';
c: 'c';
`,
src: `!; a!; ab!;`,
synErrCount: 3,
},
{
caption: "After the parser shifts the error symbol, symbols are ignored until a symbol the parser can perform shift appears",
specSrc: `
seq
: seq elem ';'
| elem ';'
| error ';' #recover
;
elem
: a b c
;
ws: "[\u{0009}\u{0020}]+" #skip;
a: 'a';
b: 'b';
c: 'c';
`,
// After the parser trasits to the error state reading the first invalid symbol ('!'),
// the second and third invalid symbols ('!') are ignored.
src: `! ! !; a!; ab!;`,
synErrCount: 3,
},
{
caption: "when the parser performs shift three times, the parser recovers from the error state",
specSrc: `
seq
: seq elem ';'
| elem ';'
| error '*' '*' ';'
;
elem
: a b c
;
ws: "[\u{0009}\u{0020}]+" #skip;
a: 'a';
b: 'b';
c: 'c';
`,
src: `!**; a!**; ab!**; abc!`,
synErrCount: 4,
},
}
for i, tt := range tests {
t.Run(fmt.Sprintf("#%v", i), func(t *testing.T) {
ast, err := spec.Parse(strings.NewReader(tt.specSrc))
if err != nil {
t.Fatal(err)
}
b := grammar.GrammarBuilder{
AST: ast,
}
g, err := b.Build()
if err != nil {
t.Fatal(err)
}
gram, err := grammar.Compile(g, grammar.SpecifyClass(grammar.ClassLALR))
if err != nil {
t.Fatal(err)
}
p, err := NewParser(gram, strings.NewReader(tt.src))
if err != nil {
t.Fatal(err)
}
err = p.Parse()
if err != nil {
t.Fatal(err)
}
synErrs := p.SyntaxErrors()
if len(synErrs) != tt.synErrCount {
t.Fatalf("unexpected syntax error; want: %v error(s), got: %v error(s)", tt.synErrCount, len(synErrs))
}
})
}
}
|
