55 lines
1.4 KiB
Go
55 lines
1.4 KiB
Go
package parsekit
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// New takes an input string and a start state,
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// and initializes the parser for it.
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func New(input string, startState StateFn) *P {
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return &P{
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input: input,
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len: len(input),
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nextState: startState,
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items: make(chan Item, 2),
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}
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}
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// Next retrieves the next parsed item.
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// When a valid item was found, then the boolean return parameter will be true.
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// On error or when successfully reaching the end of the input, false is returned.
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// When an error occurred, it will be set in the error return value, nil otherwise.
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func (p *P) Next() (Item, *Error, bool) {
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for {
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select {
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case i := <-p.items:
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switch {
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case i.Type == ItemEOF:
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return i, nil, false
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case i.Type == ItemError:
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p.err = &Error{i.Value, p.cursorRow, p.cursorColumn}
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return i, p.err, false
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default:
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p.item = i
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return i, nil, true
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}
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default:
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if p.nextState == nil {
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panic("No next state was scheduled for the parser")
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}
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p.state = p.nextState
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p.state(p)
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}
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}
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}
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// ToArray returns Parser items as an array (mainly intended for testing purposes)
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// When an error occurs during scanning, a partial result will be
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// returned, accompanied by the error that occurred.
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func (p *P) ToArray() ([]Item, *Error) {
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var items []Item
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for {
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item, err, more := p.Next()
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if !more {
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return items, err
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}
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items = append(items, item)
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}
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}
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