88 lines
1.5 KiB
Go
88 lines
1.5 KiB
Go
package ps
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import "strings"
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type PSStack []PSObject
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func NewPSStack() *PSStack {
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return &PSStack{}
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}
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func (stack *PSStack) Empty() {
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*stack = []PSObject{}
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}
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func (stack *PSStack) Push(obj PSObject) error {
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if len(*stack) > 100 {
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return ErrStackOverflow
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}
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*stack = append(*stack, obj)
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return nil
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}
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func (stack *PSStack) Pop() (PSObject, error) {
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if len(*stack) < 1 {
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return nil, ErrStackUnderflow
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}
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obj := (*stack)[len(*stack)-1]
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*stack = (*stack)[0 : len(*stack)-1]
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return obj, nil
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}
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func (stack *PSStack) PopInteger() (int, error) {
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obj, err := stack.Pop()
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if err != nil {
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return 0, err
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}
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if number, is := obj.(*PSInteger); is {
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return number.Val, nil
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} else {
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return 0, ErrTypeCheck
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}
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}
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// Pop and return the numeric value of the top of the stack as a float64.
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// Real or integer only.
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func (stack *PSStack) PopNumberAsFloat64() (float64, error) {
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obj, err := stack.Pop()
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if err != nil {
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return 0, err
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}
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if number, is := obj.(*PSReal); is {
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return number.Val, nil
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} else if number, is := obj.(*PSInteger); is {
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return float64(number.Val), nil
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} else {
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return 0, ErrTypeCheck
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}
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}
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func (pS *PSStack) String() string {
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var s strings.Builder
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s.WriteString("[ ")
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for _, obj := range *pS {
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s.WriteString(obj.String())
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s.WriteString(" ")
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}
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s.WriteString("]")
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return s.String()
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}
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func (pS *PSStack) DebugString() string {
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var s strings.Builder
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s.WriteString("[ ")
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for _, obj := range *pS {
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s.WriteString(obj.DebugString())
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s.WriteString(" ")
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}
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s.WriteString("]")
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return s.String()
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}
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