Manual

More documents

Recommendations

Info

54 Bison 2.3 • Your macro should parenthesize its arguments, if need be, since the actual arguments may not be surrounded by parentheses. Also, your macro should expand to something that can be used as a single statement when it is followed by a semicolon. 3.7 Bison Declarations The Bison declarations section of a Bison grammar defines the symbols used in formulating the grammar and the data types of semantic values. See Section 3.2 [Symbols], page 42. All token type names (but not single-character literal tokens such as ’+’ and ’*’) must be declared. Nonterminal symbols must be declared if you need to specify which data type to use for the semantic value (see Section 3.5.2 [More Than One Value Type], page 46). The first rule in the file also specifies the start symbol, by default. If you want some other symbol to be the start symbol, you must declare it explicitly (see Section 1.1 [Languages and Context-Free Grammars], page 11). 3.7.1 Require a Version of Bison You may require the minimum version of Bison to process the grammar. If the requirement is not met, bison exits with an error (exit status 63). %require "version" 3.7.2 Token Type Names The basic way to declare a token type name (terminal symbol) is as follows: %token name Bison will convert this into a #define directive in the parser, so that the function yylex (if it is in this file) can use the name name to stand for this token type’s code. Alternatively, you can use %left, %right, or %nonassoc instead of %token, if you wish to specify associativity and precedence. See Section 3.7.3 [Operator Precedence], page 55. You can explicitly specify the numeric code for a token type by appending a decimal or hexadecimal integer value in the field immediately following the token name: %token NUM 300 %token XNUM 0x12d // a GNU extension It is generally best, however, to let Bison choose the numeric codes for all token types. Bison will automatically select codes that don’t conflict with each other or with normal characters. In the event that the stack type is a union, you must augment the %token or other token declaration to include the data type alternative delimited by angle-brackets (see Section 3.5.2 [More Than One Value Type], page 46). For example: %union { /* define stack type */ double val; symrec *tptr; } %token NUM /* define token NUM and its type */ You can associate a literal string token with a token type name by writing the literal string at the end of a %token declaration which declares the name. For example:
Chapter 3: Bison Grammar Files 55 %token arrow "=>" For example, a grammar for the C language might specify these names with equivalent literal string tokens: %token OR "||" %token LE 134 "
Page 1 and 2:
Bison The Yacc-compatible Parser Ge
Page 3 and 4:
i Table of Contents Introduction .
Page 5 and 6:
4 Parser C-Language Interface . . .
Page 7 and 8:
Introduction 1 Introduction Bison i
Page 9 and 10: Conditions for Using Bison 3 Condit
Page 11 and 12: GNU GENERAL PUBLIC LICENSE 5 GNU GE
Page 13 and 14: GNU GENERAL PUBLIC LICENSE 7 Thus,
Page 15 and 16: GNU GENERAL PUBLIC LICENSE 9 which
Page 17 and 18: Chapter 1: The Concepts of Bison 11
Page 29 and 30: Chapter 2: Examples 23 2 Examples N
Page 31 and 32: Chapter 2: Examples 25 ; This defin
Page 33 and 34: Chapter 2: Examples 27 A token type
Page 35 and 36: Chapter 2: Examples 29 4 9 + 13 3 7
Page 37 and 38: Chapter 2: Examples 31 This additio
Page 39 and 40: Chapter 2: Examples 33 To this end,
Page 41 and 42: Chapter 2: Examples 35 %{ #include
Page 43 and 44: Chapter 2: Examples 37 struct init
Page 45 and 46: Chapter 2: Examples 39 } } /* Initi
Page 47 and 48: Chapter 3: Bison Grammar Files 41 3
Page 49 and 50: Chapter 3: Bison Grammar Files 43
Page 51 and 52: Chapter 3: Bison Grammar Files 45 W
Page 53 and 54: Chapter 3: Bison Grammar Files 47
Page 55 and 56: Chapter 3: Bison Grammar Files 49 a
Page 57 and 58: Chapter 3: Bison Grammar Files 51 I
Page 59: Chapter 3: Bison Grammar Files 53 I
Page 63 and 64: Chapter 3: Bison Grammar Files 57 3
Page 65 and 66: Chapter 3: Bison Grammar Files 59 T
Page 67 and 68: Chapter 3: Bison Grammar Files 61 T
Page 69 and 70: Chapter 4: Parser C-Language Interf
Page 77 and 78: Chapter 5: The Bison Parser Algorit
Page 89 and 90: Chapter 6: Error Recovery 83 6 Erro
Page 91 and 92: Chapter 7: Handling Context Depende
Page 93 and 94: Chapter 7: Handling Context Depende
Page 95 and 96: Chapter 8: Debugging Your Parser 89
Page 103 and 104: Chapter 9: Invoking Bison 97 9 Invo
Page 105 and 106: Chapter 9: Invoking Bison 99 ‘--d
Page 107 and 108: Chapter 10: C++ Language Interface
Page 109 and 110: Chapter 10: C++ Language Interface
Page 111 and 112:
Chapter 10: C++ Language Interface
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Chapter 11: Frequently Asked Questi
Page 119 and 120:
Page 121 and 122:
Page 123 and 124:
Appendix A: Bison Symbols 117 Appen
Page 125 and 126:
Appendix A: Bison Symbols 119 two s
Page 127 and 128:
Appendix A: Bison Symbols 121 or (i
Page 129 and 130:
Appendix B: Glossary 123 Appendix B
Page 131 and 132:
Appendix B: Glossary 125 Reverse po
Page 133 and 134:
Appendix C: Copying This Manual 127
Page 135 and 136:
Page 137 and 138:
Page 139 and 140:
Page 141 and 142:
Index 135 Index $ $$ . . . . . . .
Page 143 and 144:
Index 137 LALR(1) grammars . . . .
show all

Manual

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?