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package syntax_test
import (
"bytes"
"fmt"
"log"
"reflect"
"strings"
"testing"
"go.starlark.net/syntax"
)
func TestWalk(t *testing.T) {
const src = `
for x in y:
if x:
pass
else:
f([2*x for x in "abc"])
`
// TODO(adonovan): test that it finds all syntax.Nodes
// (compare against a reflect-based implementation).
// TODO(adonovan): test that the result of f is used to prune
// the descent.
f, err := syntax.Parse("hello.go", src, 0)
if err != nil {
t.Fatal(err)
}
var buf bytes.Buffer
var depth int
syntax.Walk(f, func(n syntax.Node) bool {
if n == nil {
depth--
return true
}
fmt.Fprintf(&buf, "%s%s\n",
strings.Repeat(" ", depth),
strings.TrimPrefix(reflect.TypeOf(n).String(), "*syntax."))
depth++
return true
})
got := buf.String()
want := `
File
ForStmt
Ident
Ident
IfStmt
Ident
BranchStmt
ExprStmt
CallExpr
Ident
Comprehension
BinaryExpr
Literal
Ident
ForClause
Ident
Literal`
got = strings.TrimSpace(got)
want = strings.TrimSpace(want)
if got != want {
t.Errorf("got %s, want %s", got, want)
}
}
// ExampleWalk demonstrates the use of Walk to
// enumerate the identifiers in a Starlark source file
// containing a nonsense program with varied grammar.
func ExampleWalk() {
const src = `
load("library", "a")
def b(c, *, d=e):
f += {g: h}
i = -(j)
return k.l[m + n]
for o in [p for q, r in s if t]:
u(lambda: v, w[x:y:z])
`
f, err := syntax.Parse("hello.star", src, 0)
if err != nil {
log.Fatal(err)
}
var idents []string
syntax.Walk(f, func(n syntax.Node) bool {
if id, ok := n.(*syntax.Ident); ok {
idents = append(idents, id.Name)
}
return true
})
fmt.Println(strings.Join(idents, " "))
// The identifier 'a' appears in both LoadStmt.From[0] and LoadStmt.To[0].
// Output:
// a a b c d e f g h i j k l m n o p q r s t u v w x y z
}
|
