mirror of
https://github.com/robertkrimen/otto
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50ed21f88e
* (#257) Change Walk/Visit to follow an explicit Enter/Exit pattern * (#257) Convert walk example into test. * (#257) restore walk/visitor example * (#257) Fix godoc comment in the Visitor interface ... typo referred to `End` method instead of `Exit`
83 lines
1.6 KiB
Go
83 lines
1.6 KiB
Go
package ast_test
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import (
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"log"
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"testing"
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"github.com/robertkrimen/otto/ast"
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"github.com/robertkrimen/otto/file"
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"github.com/robertkrimen/otto/parser"
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)
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type walker struct {
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stack []ast.Node
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source string
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shift file.Idx
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}
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// push and pop below are to prove the symmetry of Enter/Exit calls
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func (w *walker) push(n ast.Node) {
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w.stack = append(w.stack, n)
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}
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func (w *walker) pop(n ast.Node) {
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size := len(w.stack)
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if size <= 0 {
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panic("pop of empty stack")
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}
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toPop := w.stack[size-1]
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if toPop != n {
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panic("pop: nodes do not equal")
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}
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w.stack[size-1] = nil
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w.stack = w.stack[:size-1]
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}
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func (w *walker) Enter(n ast.Node) ast.Visitor {
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w.push(n)
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if id, ok := n.(*ast.Identifier); ok && id != nil {
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idx := n.Idx0() + w.shift - 1
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s := w.source[:idx] + "new_" + w.source[idx:]
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w.source = s
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w.shift += 4
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}
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if v, ok := n.(*ast.VariableExpression); ok && v != nil {
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idx := n.Idx0() + w.shift - 1
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s := w.source[:idx] + "varnew_" + w.source[idx:]
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w.source = s
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w.shift += 7
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}
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return w
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}
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func (w *walker) Exit(n ast.Node) {
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w.pop(n)
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}
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func TestVisitorRewrite(t *testing.T) {
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source := `var b = function() {test(); try {} catch(e) {} var test = "test(); var test = 1"} // test`
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program, err := parser.ParseFile(nil, "", source, 0)
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if err != nil {
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log.Fatal(err)
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}
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w := &walker{source: source}
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ast.Walk(w, program)
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xformed := `var varnew_b = function() {new_test(); try {} catch(new_e) {} var varnew_test = "test(); var test = 1"} // test`
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if w.source != xformed {
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t.Errorf("source is `%s` not `%s`", w.source, xformed)
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}
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if len(w.stack) != 0 {
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t.Errorf("stack should be empty, but is length: %d", len(w.stack))
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}
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}
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