func TestWalk(t *testing.T) {
g := ast.Grammar([]*ast.Production{
{
Name: &ast.Name{Name: "E"},
Expr: ast.Alternative([]ast.Expression{
ast.Sequence([]ast.Expression{
&ast.Name{Name: "T"},
&ast.Terminal{Terminal: "+"},
&ast.Name{Name: "T"},
}),
&ast.Name{Name: "T"},
&ast.Epsilon{Epsilon: "e"},
}),
},
{
Name: &ast.Name{Name: "T"},
Expr: ast.Alternative([]ast.Expression{
ast.Sequence([]ast.Expression{
&ast.Terminal{Terminal: "("},
&ast.Name{Name: "T"},
&ast.Terminal{Terminal: ")"},
}),
&ast.Name{Name: "T"},
}),
},
})
order := []string{
"ast.Grammar",
"*ast.Production",
"*ast.Name",
"ast.Alternative",
"ast.Sequence",
"*ast.Name",
"*ast.Terminal",
"*ast.Name",
"*ast.Name",
"*ast.Epsilon",
"*ast.Production",
"*ast.Name",
"ast.Alternative",
"ast.Sequence",
"*ast.Terminal",
"*ast.Name",
"*ast.Terminal",
"*ast.Name",
}
i := 0
ast.Walk(func(n ast.Node) bool {
if n == nil {
return false
}
if typ := reflect.TypeOf(n).String(); order[i] != typ {
t.Errorf("got %q want %q", typ, order[i])
}
i++
return true
}, g)
}
func TestFprint(t *testing.T) {
const expected = `Expr → Term "+" Expr | Term "-" Expr | Term | ε .
Term → Factor "*" Term | Factor "/" Term | Factor .
Factor → "(" Expr ")" | Number .
Number → Digit | Digit Number .
Digit → "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" .`
g := ast.Grammar([]*ast.Production{
{
Name: &ast.Name{Name: "Expr"},
Expr: ast.Alternative([]ast.Expression{
ast.Sequence([]ast.Expression{
&ast.Name{Name: "Term"},
&ast.Terminal{Terminal: "+"},
&ast.Name{Name: "Expr"},
}),
ast.Sequence([]ast.Expression{
&ast.Name{Name: "Term"},
&ast.Terminal{Terminal: "-"},
&ast.Name{Name: "Expr"},
}),
&ast.Name{Name: "Term"},
&ast.Epsilon{Epsilon: "e"},
}),
},
{
Name: &ast.Name{Name: "Term"},
Expr: ast.Alternative([]ast.Expression{
ast.Sequence([]ast.Expression{
&ast.Name{Name: "Factor"},
&ast.Terminal{Terminal: "*"},
&ast.Name{Name: "Term"},
}),
ast.Sequence([]ast.Expression{
&ast.Name{Name: "Factor"},
&ast.Terminal{Terminal: "/"},
&ast.Name{Name: "Term"},
}),
&ast.Name{Name: "Factor"},
}),
},
{
Name: &ast.Name{Name: "Factor"},
Expr: ast.Alternative([]ast.Expression{
ast.Sequence([]ast.Expression{
&ast.Terminal{Terminal: "("},
&ast.Name{Name: "Expr"},
&ast.Terminal{Terminal: ")"},
}),
&ast.Name{Name: "Number"},
}),
},
{
Name: &ast.Name{Name: "Number"},
Expr: ast.Alternative([]ast.Expression{
&ast.Name{Name: "Digit"},
ast.Sequence([]ast.Expression{
&ast.Name{Name: "Digit"},
&ast.Name{Name: "Number"},
}),
}),
},
{
Name: &ast.Name{Name: "Digit"},
Expr: ast.Alternative([]ast.Expression{
&ast.Terminal{Terminal: "0"}, &ast.Terminal{Terminal: "1"},
&ast.Terminal{Terminal: "2"}, &ast.Terminal{Terminal: "3"},
&ast.Terminal{Terminal: "4"}, &ast.Terminal{Terminal: "5"},
&ast.Terminal{Terminal: "6"}, &ast.Terminal{Terminal: "7"},
&ast.Terminal{Terminal: "8"}, &ast.Terminal{Terminal: "9"},
}),
},
})
var buf bytes.Buffer
if err := printer.Fprint(&buf, g); err != nil {
t.Errorf("error: %v", err)
}
if actual := buf.String(); actual != expected {
t.Errorf("got\n'%s'\nwant\n'%s'", actual, expected)
}
}
func TestParse(t *testing.T) {
const src = `Start -> Expr.
Expr → Term "+" Expr | Term "-" Expr | Term | ε.
Term → Factor "*" Term | Factor "/" Term | Factor .
Factor → "(" Expr ")" | Number .
Number → Digit | Digit Number .
Digit → "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" .`
expected := ast.Grammar([]*ast.Production{
{
Name: &ast.Name{Name: "Start"},
Expr: &ast.Name{Name: "Expr"},
},
{
Name: &ast.Name{Name: "Expr"},
Expr: ast.Alternative([]ast.Expression{
ast.Sequence([]ast.Expression{
&ast.Name{Name: "Term"},
&ast.Terminal{Terminal: "+"},
&ast.Name{Name: "Expr"},
}),
ast.Sequence([]ast.Expression{
&ast.Name{Name: "Term"},
&ast.Terminal{Terminal: "-"},
&ast.Name{Name: "Expr"},
}),
&ast.Name{Name: "Term"},
&ast.Epsilon{Epsilon: "ε"},
}),
},
{
Name: &ast.Name{Name: "Term"},
Expr: ast.Alternative([]ast.Expression{
ast.Sequence([]ast.Expression{
&ast.Name{Name: "Factor"},
&ast.Terminal{Terminal: "*"},
&ast.Name{Name: "Term"},
}),
ast.Sequence([]ast.Expression{
&ast.Name{Name: "Factor"},
&ast.Terminal{Terminal: "/"},
&ast.Name{Name: "Term"},
}),
&ast.Name{Name: "Factor"},
}),
},
{
Name: &ast.Name{Name: "Factor"},
Expr: ast.Alternative([]ast.Expression{
ast.Sequence([]ast.Expression{
&ast.Terminal{Terminal: "("},
&ast.Name{Name: "Expr"},
&ast.Terminal{Terminal: ")"},
}),
&ast.Name{Name: "Number"},
}),
},
{
Name: &ast.Name{Name: "Number"},
Expr: ast.Alternative([]ast.Expression{
&ast.Name{Name: "Digit"},
ast.Sequence([]ast.Expression{
&ast.Name{Name: "Digit"},
&ast.Name{Name: "Number"},
}),
}),
},
{
Name: &ast.Name{Name: "Digit"},
Expr: ast.Alternative([]ast.Expression{
&ast.Terminal{Terminal: "0"}, &ast.Terminal{Terminal: "1"},
&ast.Terminal{Terminal: "2"}, &ast.Terminal{Terminal: "3"},
&ast.Terminal{Terminal: "4"}, &ast.Terminal{Terminal: "5"},
&ast.Terminal{Terminal: "6"}, &ast.Terminal{Terminal: "7"},
&ast.Terminal{Terminal: "8"}, &ast.Terminal{Terminal: "9"},
}),
},
})
g, err := parser.Parse([]byte(src), "test")
if err != nil {
t.Errorf("error: %v", err)
}
check(t, g, expected)
}
package generator
import (
"testing"
"github.com/davidrjenni/pg/ast"
)
var testGrammar = ast.Grammar([]*ast.Production{
{
Name: &ast.Name{Name: "E"},
Expr: ast.Alternative([]ast.Expression{
&ast.Name{Name: "T"},
ast.Sequence([]ast.Expression{
&ast.Name{Name: "E"},
&ast.Terminal{Terminal: "+"},
&ast.Name{Name: "T"},
}),
}),
},
{
Name: &ast.Name{Name: "T"},
Expr: ast.Alternative([]ast.Expression{
&ast.Name{Name: "F"},
ast.Sequence([]ast.Expression{
&ast.Name{Name: "T"},
&ast.Terminal{Terminal: "*"},
&ast.Name{Name: "F"},
}),
}),
},