52 lines
1.5 KiB
Go
52 lines
1.5 KiB
Go
/*
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* MIT License
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*
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* Copyright (c) 2021 zeromicro
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*/
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package parser
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import (
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"unicode"
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"github.com/antlr/antlr4/runtime/Go/antlr"
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)
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type CaseChangingStream struct {
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antlr.CharStream
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upper bool
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}
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// newCaseChangingStream returns a new CaseChangingStream that forces
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// all tokens read from the underlying stream to be either upper case
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// or lower case based on the upper argument.
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func newCaseChangingStream(in antlr.CharStream, upper bool) *CaseChangingStream {
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return &CaseChangingStream{in, upper}
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}
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// LA gets the value of the symbol at offset from the current position
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// from the underlying CharStream and converts it to either upper case
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// or lower case.
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func (is *CaseChangingStream) LA(offset int) int {
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in := is.CharStream.LA(offset)
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if in < 0 {
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// Such as antlr.TokenEOF which is -1
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return in
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}
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if is.upper {
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return int(unicode.ToUpper(rune(in)))
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}
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return int(unicode.ToLower(rune(in)))
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}
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