forked from vikunja/vikunja
53 lines
1.2 KiB
Go
53 lines
1.2 KiB
Go
package ast
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import "fmt"
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// WalkFunc describes a function to be called for each node during a Walk. The
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// returned node can be used to rewrite the AST. Walking stops the returned
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// bool is false.
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type WalkFunc func(Node) (Node, bool)
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// Walk traverses an AST in depth-first order: It starts by calling fn(node);
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// node must not be nil. If fn returns true, Walk invokes fn recursively for
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// each of the non-nil children of node, followed by a call of fn(nil). The
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// returned node of fn can be used to rewrite the passed node to fn.
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func Walk(node Node, fn WalkFunc) Node {
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rewritten, ok := fn(node)
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if !ok {
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return rewritten
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}
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switch n := node.(type) {
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case *File:
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n.Node = Walk(n.Node, fn)
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case *ObjectList:
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for i, item := range n.Items {
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n.Items[i] = Walk(item, fn).(*ObjectItem)
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}
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case *ObjectKey:
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// nothing to do
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case *ObjectItem:
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for i, k := range n.Keys {
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n.Keys[i] = Walk(k, fn).(*ObjectKey)
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}
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if n.Val != nil {
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n.Val = Walk(n.Val, fn)
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}
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case *LiteralType:
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// nothing to do
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case *ListType:
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for i, l := range n.List {
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n.List[i] = Walk(l, fn)
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}
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case *ObjectType:
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n.List = Walk(n.List, fn).(*ObjectList)
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default:
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// should we panic here?
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fmt.Printf("unknown type: %T\n", n)
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}
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fn(nil)
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return rewritten
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}
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