61 lines
1.2 KiB
Go
61 lines
1.2 KiB
Go
package main
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var (
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unknownVarType gotype = gotype{Plain: `unknown`} // placeholder
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mixedVarType gotype = gotype{Plain: `mixed`} // when setting an incompatible type
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)
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type LocalVar struct {
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Name string
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Type gotype
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}
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type Scope struct {
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parent *Scope
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locals []LocalVar
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}
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func NewScope() *Scope {
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return &Scope{}
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}
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func (this *Scope) NewScope() *Scope {
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return &Scope{
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parent: this,
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}
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}
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func (this *Scope) Has(varName string) *LocalVar {
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for idx := range this.locals {
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if this.locals[idx].Name == varName {
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return &this.locals[idx] // Mutable
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}
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}
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if this.parent != nil {
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return this.parent.Has(varName)
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}
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return nil // not found
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}
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func (this *Scope) Set(Name string, Type gotype) *LocalVar {
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if lv := this.Has(Name); lv != nil {
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// Update known type for existing variable
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if lv.Type.Equals(&unknownVarType) {
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lv.Type = Type
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} else if lv.Type.Equals(&Type) {
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// no-op, more evidence for the same type
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} else if !lv.Type.Equals(&Type) {
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// conflicting type information
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lv.Type = mixedVarType
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}
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return lv
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}
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// Insert new
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this.locals = append(this.locals, LocalVar{Name: Name, Type: Type})
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return &this.locals[len(this.locals)-1]
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}
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