44 lines
855 B
Go
44 lines
855 B
Go
// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
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// All rights reserved.
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// operator-length.go
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package expr
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//-------- length term
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func newLengthTerm(tk *Token) (inst *term) {
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return &term{
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tk: *tk,
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children: make([]*term, 0, 1),
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position: posPrefix,
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priority: priSign,
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evalFunc: evalLength,
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}
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}
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func evalLength(ctx ExprContext, self *term) (v any, err error) {
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var rightValue any
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if rightValue, err = self.evalPrefix(ctx); err != nil {
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return
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}
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if isList(rightValue) {
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list, _ := rightValue.([]any)
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v = len(list)
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} else if isString(rightValue) {
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s, _ := rightValue.(string)
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v = len(s)
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} else if it, ok := rightValue.(Iterator); ok {
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v = it.Index()
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} else {
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err = self.errIncompatibleType(rightValue)
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}
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return
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}
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// init
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func init() {
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registerTermConstructor(SymHash, newLengthTerm)
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}
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