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|
package grammar
import (
"strings"
"testing"
"github.com/nihei9/vartan/spec"
)
type first struct {
lhs string
num int
dot int
symbols []string
empty bool
}
func TestGenFirst(t *testing.T) {
tests := []struct {
caption string
src string
first []first
}{
{
caption: "productions contain only non-empty productions",
src: `
%name test
expr
: expr add term
| term
;
term
: term mul factor
| factor
;
factor
: l_paren expr r_paren
| id
;
add: "\+";
mul: "\*";
l_paren: "\(";
r_paren: "\)";
id: "[A-Za-z_][0-9A-Za-z_]*";
`,
first: []first{
{lhs: "expr'", num: 0, dot: 0, symbols: []string{"l_paren", "id"}},
{lhs: "expr", num: 0, dot: 0, symbols: []string{"l_paren", "id"}},
{lhs: "expr", num: 0, dot: 1, symbols: []string{"add"}},
{lhs: "expr", num: 0, dot: 2, symbols: []string{"l_paren", "id"}},
{lhs: "expr", num: 1, dot: 0, symbols: []string{"l_paren", "id"}},
{lhs: "term", num: 0, dot: 0, symbols: []string{"l_paren", "id"}},
{lhs: "term", num: 0, dot: 1, symbols: []string{"mul"}},
{lhs: "term", num: 0, dot: 2, symbols: []string{"l_paren", "id"}},
{lhs: "term", num: 1, dot: 0, symbols: []string{"l_paren", "id"}},
{lhs: "factor", num: 0, dot: 0, symbols: []string{"l_paren"}},
{lhs: "factor", num: 0, dot: 1, symbols: []string{"l_paren", "id"}},
{lhs: "factor", num: 0, dot: 2, symbols: []string{"r_paren"}},
{lhs: "factor", num: 1, dot: 0, symbols: []string{"id"}},
},
},
{
caption: "productions contain the empty start production",
src: `
%name test
s
:
;
`,
first: []first{
{lhs: "s'", num: 0, dot: 0, symbols: []string{}, empty: true},
{lhs: "s", num: 0, dot: 0, symbols: []string{}, empty: true},
},
},
{
caption: "productions contain an empty production",
src: `
%name test
s
: foo bar
;
foo
:
;
bar: "bar";
`,
first: []first{
{lhs: "s'", num: 0, dot: 0, symbols: []string{"bar"}, empty: false},
{lhs: "s", num: 0, dot: 0, symbols: []string{"bar"}, empty: false},
{lhs: "foo", num: 0, dot: 0, symbols: []string{}, empty: true},
},
},
{
caption: "a start production contains a non-empty alternative and empty alternative",
src: `
%name test
s
: foo
|
;
foo: "foo";
`,
first: []first{
{lhs: "s'", num: 0, dot: 0, symbols: []string{"foo"}, empty: true},
{lhs: "s", num: 0, dot: 0, symbols: []string{"foo"}},
{lhs: "s", num: 1, dot: 0, symbols: []string{}, empty: true},
},
},
{
caption: "a production contains non-empty alternative and empty alternative",
src: `
%name test
s
: foo
;
foo
: bar
|
;
bar: "bar";
`,
first: []first{
{lhs: "s'", num: 0, dot: 0, symbols: []string{"bar"}, empty: true},
{lhs: "s", num: 0, dot: 0, symbols: []string{"bar"}, empty: true},
{lhs: "foo", num: 0, dot: 0, symbols: []string{"bar"}},
{lhs: "foo", num: 1, dot: 0, symbols: []string{}, empty: true},
},
},
}
for _, tt := range tests {
t.Run(tt.caption, func(t *testing.T) {
fst, gram := genActualFirst(t, tt.src)
for _, ttFirst := range tt.first {
lhsSym, ok := gram.symbolTable.toSymbol(ttFirst.lhs)
if !ok {
t.Fatalf("a symbol was not found; symbol: %v", ttFirst.lhs)
}
prod, ok := gram.productionSet.findByLHS(lhsSym)
if !ok {
t.Fatalf("a production was not found; LHS: %v (%v)", ttFirst.lhs, lhsSym)
}
actualFirst, err := fst.find(prod[ttFirst.num], ttFirst.dot)
if err != nil {
t.Fatalf("failed to get a FIRST set; LHS: %v (%v), num: %v, dot: %v, error: %v", ttFirst.lhs, lhsSym, ttFirst.num, ttFirst.dot, err)
}
expectedFirst := genExpectedFirstEntry(t, ttFirst.symbols, ttFirst.empty, gram.symbolTable)
testFirst(t, actualFirst, expectedFirst)
}
})
}
}
func genActualFirst(t *testing.T, src string) (*firstSet, *Grammar) {
ast, err := spec.Parse(strings.NewReader(src))
if err != nil {
t.Fatal(err)
}
b := GrammarBuilder{
AST: ast,
}
gram, err := b.Build()
if err != nil {
t.Fatal(err)
}
fst, err := genFirstSet(gram.productionSet)
if err != nil {
t.Fatal(err)
}
if fst == nil {
t.Fatal("genFiest returned nil without any error")
}
return fst, gram
}
func genExpectedFirstEntry(t *testing.T, symbols []string, empty bool, symTab *symbolTable) *firstEntry {
t.Helper()
entry := newFirstEntry()
if empty {
entry.addEmpty()
}
for _, sym := range symbols {
symSym, ok := symTab.toSymbol(sym)
if !ok {
t.Fatalf("a symbol was not found; symbol: %v", sym)
}
entry.add(symSym)
}
return entry
}
func testFirst(t *testing.T, actual, expected *firstEntry) {
if actual.empty != expected.empty {
t.Errorf("empty is mismatched\nwant: %v\ngot: %v", expected.empty, actual.empty)
}
if len(actual.symbols) != len(expected.symbols) {
t.Fatalf("invalid FIRST set\nwant: %+v\ngot: %+v", expected.symbols, actual.symbols)
}
for eSym := range expected.symbols {
if _, ok := actual.symbols[eSym]; !ok {
t.Fatalf("invalid FIRST set\nwant: %+v\ngot: %+v", expected.symbols, actual.symbols)
}
}
}
|
