84 lines
2.0 KiB
Go
84 lines
2.0 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package token defines constants representing the lexical tokens of the gcfg
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// configuration syntax and basic operations on tokens (printing, predicates).
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//
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// Note that the API for the token package may change to accommodate new
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// features or implementation changes in gcfg.
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//
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package token
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import "strconv"
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// Token is the set of lexical tokens of the gcfg configuration syntax.
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type Token int
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// The list of tokens.
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const (
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// Special tokens
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ILLEGAL Token = iota
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EOF
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COMMENT
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literal_beg
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// Identifiers and basic type literals
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// (these tokens stand for classes of literals)
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IDENT // section-name, variable-name
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STRING // "subsection-name", variable value
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literal_end
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operator_beg
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// Operators and delimiters
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ASSIGN // =
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LBRACK // [
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RBRACK // ]
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EOL // \n
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operator_end
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)
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var tokens = [...]string{
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ILLEGAL: "ILLEGAL",
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EOF: "EOF",
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COMMENT: "COMMENT",
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IDENT: "IDENT",
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STRING: "STRING",
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ASSIGN: "=",
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LBRACK: "[",
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RBRACK: "]",
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EOL: "\n",
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}
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// String returns the string corresponding to the token tok.
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// For operators and delimiters, the string is the actual token character
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// sequence (e.g., for the token ASSIGN, the string is "="). For all other
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// tokens the string corresponds to the token constant name (e.g. for the
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// token IDENT, the string is "IDENT").
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//
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func (tok Token) String() string {
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s := ""
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if 0 <= tok && tok < Token(len(tokens)) {
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s = tokens[tok]
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}
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if s == "" {
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s = "token(" + strconv.Itoa(int(tok)) + ")"
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}
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return s
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}
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// Predicates
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// IsLiteral returns true for tokens corresponding to identifiers
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// and basic type literals; it returns false otherwise.
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//
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func (tok Token) IsLiteral() bool { return literal_beg < tok && tok < literal_end }
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// IsOperator returns true for tokens corresponding to operators and
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// delimiters; it returns false otherwise.
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//
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func (tok Token) IsOperator() bool { return operator_beg < tok && tok < operator_end }
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