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package ast |
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type Reference int |
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const InvalidReference Reference = -1 |
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func (r Reference) Valid() bool { |
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return r != InvalidReference |
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} |
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type Builder struct { |
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tree Root |
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lastIdx int |
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} |
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func (b *Builder) Tree() *Root { |
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return &b.tree |
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} |
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func (b *Builder) NodeAt(ref Reference) *Node { |
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return b.tree.at(ref) |
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} |
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func (b *Builder) Reset() { |
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b.tree.nodes = b.tree.nodes[:0] |
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b.lastIdx = 0 |
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} |
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func (b *Builder) Push(n Node) Reference { |
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b.lastIdx = len(b.tree.nodes) |
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b.tree.nodes = append(b.tree.nodes, n) |
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return Reference(b.lastIdx) |
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} |
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func (b *Builder) PushAndChain(n Node) Reference { |
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newIdx := len(b.tree.nodes) |
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b.tree.nodes = append(b.tree.nodes, n) |
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if b.lastIdx >= 0 { |
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b.tree.nodes[b.lastIdx].next = newIdx - b.lastIdx |
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} |
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b.lastIdx = newIdx |
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return Reference(b.lastIdx) |
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} |
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func (b *Builder) AttachChild(parent Reference, child Reference) { |
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b.tree.nodes[parent].child = int(child) - int(parent) |
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} |
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func (b *Builder) Chain(from Reference, to Reference) { |
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b.tree.nodes[from].next = int(to) - int(from) |
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} |