M.V. Hutz
f3b9137d75
Closes #26 - Added -i flag to select interpreter (lambda or debruijn) - Created debruijn package with Expression interface - Variable contains index and optional label - Abstraction contains only body (no parameter) - Application structure remains similar - Implemented De Bruijn reduction without variable renaming - Shift operation handles index adjustments - Substitute replaces by index instead of name - Abstracted Engine into interface with two implementations - LambdaEngine: original named variable engine - DeBruijnEngine: new index-based engine - Added conversion functions between representations - LambdaToDeBruijn: converts named to indexed - DeBruijnToLambda: converts indexed back to named - SaccharineToDeBruijn: direct saccharine to De Bruijn - Updated main to switch engines based on -i flag - All test samples pass with both engines Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
69 lines
1.1 KiB
Go
69 lines
1.1 KiB
Go
package debruijn
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type Iterator struct {
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trace []*Expression
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}
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func NewIterator(expr *Expression) *Iterator {
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return &Iterator{[]*Expression{expr}}
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}
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func (i *Iterator) Done() bool {
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return len(i.trace) == 0
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}
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func (i *Iterator) Current() *Expression {
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if i.Done() {
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return nil
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}
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return i.trace[len(i.trace)-1]
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}
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func (i *Iterator) Parent() *Expression {
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if len(i.trace) < 2 {
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return nil
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}
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return i.trace[len(i.trace)-2]
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}
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func (i *Iterator) Swap(with Expression) {
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current := i.Current()
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if current != nil {
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*current = with
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}
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}
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func (i *Iterator) Back() bool {
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if i.Done() {
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return false
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}
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i.trace = i.trace[:len(i.trace)-1]
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return true
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}
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func (i *Iterator) Next() {
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switch typed := (*i.Current()).(type) {
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case *Abstraction:
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i.trace = append(i.trace, &typed.body)
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case *Application:
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i.trace = append(i.trace, &typed.abstraction)
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case *Variable:
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for len(i.trace) > 1 {
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if app, ok := (*i.Parent()).(*Application); ok {
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if app.abstraction == *i.Current() {
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i.Back()
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i.trace = append(i.trace, &app.argument)
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return
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}
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}
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i.Back()
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}
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i.trace = []*Expression{}
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}
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}
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