mirror of
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71 lines
1.5 KiB
Go
71 lines
1.5 KiB
Go
package eval
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import "github.com/elves/elvish/parse"
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type argsWalker struct {
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cp *compiler
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form *parse.Form
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idx int
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}
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func (cp *compiler) walkArgs(f *parse.Form) *argsWalker {
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return &argsWalker{cp, f, 0}
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}
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func (aw *argsWalker) more() bool {
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return aw.idx < len(aw.form.Args)
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}
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func (aw *argsWalker) peek() *parse.Compound {
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if !aw.more() {
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aw.cp.errorpf(aw.form.End(), aw.form.End(), "need more arguments")
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}
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return aw.form.Args[aw.idx]
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}
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func (aw *argsWalker) next() *parse.Compound {
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n := aw.peek()
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aw.idx++
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return n
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}
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// nextIs returns whether the next argument's source matches the given text. It
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// also consumes the argument if it is.
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func (aw *argsWalker) nextIs(text string) bool {
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if aw.more() && aw.form.Args[aw.idx].SourceText() == text {
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aw.idx++
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return true
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}
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return false
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}
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// nextMustLambda fetches the next argument, raising an error if it is not a
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// lambda.
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func (aw *argsWalker) nextMustLambda() *parse.Primary {
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n := aw.next()
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if len(n.Indexings) != 1 {
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aw.cp.errorpf(n.Begin(), n.End(), "must be lambda")
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}
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if len(n.Indexings[0].Indicies) != 0 {
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aw.cp.errorpf(n.Begin(), n.End(), "must be lambda")
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}
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pn := n.Indexings[0].Head
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if pn.Type != parse.Lambda {
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aw.cp.errorpf(n.Begin(), n.End(), "must be lambda")
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}
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return pn
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}
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func (aw *argsWalker) nextMustLambdaIfAfter(leader string) *parse.Primary {
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if aw.nextIs(leader) {
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return aw.nextMustLambda()
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}
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return nil
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}
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func (aw *argsWalker) mustEnd() {
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if aw.more() {
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aw.cp.errorpf(aw.form.Args[aw.idx].Begin(), aw.form.End(), "too many arguments")
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}
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}
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