"TCPL/A.13_Grammar"版本比较

A.13 Grammar

Below is a recapitulation of the grammar that was given throughout the earlier part of this appendix. It has exactly the same content, but is in different order.

The grammar has undefined terminal symbols integer-constant, character-constant, floating-constant, identifier, string, and enumeration-constant; the typewriter style words and symbols are terminals given literally. This grammar can be transformed mechanically into input acceptable for an automatic parser-generator. Besides adding whatever syntactic marking is used to indicate alternatives in productions, it is necessary to expand the one of constructions, and (depending on the rules of the parser-generator) to duplicate each production with an opt symbol, once with the symbol and once without. With one further change, namely deleting the production typedef-name: identifier and making typedef-name a terminal symbol, this grammar is acceptable to the YACC parser-generator. It has only one conflict, generated by the if-else ambiguity.

• translation-unit:
  • external-declaration translation-unit external-declaration
  external-declaration:
  • function-definition declaration
  function-definition:
  • declaration-specifiersopt declarator declaration-listopt compound-statement
  declaration:
  • declaration-specifiers init-declarator-listopt;
  declaration-list:
  • declaration declaration-list declaration
  declaration-specifiers:
  • storage-class-specifier declaration-specifiersopt type-specifier declaration-specifiersopt type-qualifier declaration-specifiersopt
  storage-class specifier: one of
  • auto register static extern typedef
  type specifier: one of
  • void char short int long float double signed unsigned struct-or-union-specifier enum-specifier typedef-name
  type-qualifier: one of
  • const volatile
  struct-or-union-specifier:
  • struct-or-union identifieropt { struct-declaration-list } struct-or-union identifier
  struct-or-union: one of
  • struct union
  struct-declaration-list:
  • struct declaration struct-declaration-list struct declaration
  init-declarator-list:
  • init-declarator init-declarator-list, init-declarator
  init-declarator:
  • declarator declarator = initializer
  struct-declaration:
  • specifier-qualifier-list struct-declarator-list;
  specifier-qualifier-list:
  • type-specifier specifier-qualifier-listopt type-qualifier specifier-qualifier-listopt
  struct-declarator-list:
  • struct-declarator struct-declarator-list , struct-declarator
  struct-declarator:
  • declarator declaratoropt : constant-expression
  enum-specifier:
  • enum identifieropt { enumerator-list } enum identifier
  enumerator-list:
  • enumerator enumerator-list , enumerator
  enumerator:
  • identifier identifier = constant-expression
  declarator:
  • pointeropt direct-declarator
  direct-declarator:
  • identifier (declarator) direct-declarator [ constant-expressionopt ] direct-declarator ( parameter-type-list ) direct-declarator ( identifier-listopt )
  pointer:
  • type-qualifier-listopt
  • type-qualifier-listopt pointer
  type-qualifier-list:
  • type-qualifier type-qualifier-list type-qualifier
  parameter-type-list:
  • parameter-list parameter-list , ...
  parameter-list:
  • parameter-declaration parameter-list , parameter-declaration
  parameter-declaration:
  • declaration-specifiers declarator declaration-specifiers abstract-declaratoropt
  identifier-list:
  • identifier identifier-list , identifier
  initializer:
  • assignment-expression { initializer-list } { initializer-list , }
  initializer-list:
  • initializer initializer-list , initializer
  type-name:
  • specifier-qualifier-list abstract-declaratoropt
  abstract-declarator:
  • pointer pointeropt direct-abstract-declarator
  direct-abstract-declarator:
  • ( abstract-declarator ) direct-abstract-declaratoropt [constant-expressionopt] direct-abstract-declaratoropt (parameter-type-listopt)
  typedef-name:
  • identifier
  statement:
  • labeled-statement expression-statement compound-statement selection-statement iteration-statement jump-statement
  labeled-statement:
  • identifier : statement case constant-expression : statement default : statement
  expression-statement:
  • expressionopt;
  compound-statement:
  • { declaration-listopt statement-listopt }
  statement-list:
  • statement statement-list statement
  selection-statement:
  • if (expression) statement if (expression) statement else statement switch (expression) statement
  iteration-statement:
  • while (expression) statement do statement while (expression); for (expressionopt; expressionopt; expressionopt) statement
  jump-statement:
  • goto identifier; continue; break; return expressionopt;
  expression:
  • assignment-expression expression , assignment-expression
  assignment-expression:
  • conditional-expression unary-expression assignment-operator assignment-expression
  assignment-operator: one of

  • = *= /= %= += -= <<= >>= &= ^= |=

  conditional-expression:
  • logical-OR-expression logical-OR-expression ? expression : conditional-expression
  constant-expression:
  • conditional-expression
  logical-OR-expression:
  • logical-AND-expression

    logical-OR-expression || logical-AND-expression

  logical-AND-expression:
  • inclusive-OR-expression

    logical-AND-expression && inclusive-OR-expression

  inclusive-OR-expression:
  • exclusive-OR-expression inclusive-OR-expression | exclusive-OR-expression
  exclusive-OR-expression:
  • AND-expression exclusive-OR-expression ^ AND-expression
  AND-expression:
  • equality-expression

    AND-expression & equality-expression

  equality-expression:
  • relational-expression equality-expression == relational-expression equality-expression != relational-expression
  relational-expression:
  • shift-expression

    relational-expression < shift-expression relational-expression > shift-expression relational-expression <= shift-expression relational-expression >= shift-expression

  shift-expression:
  • additive-expression

    shift-expression << additive-expression shift-expression >> additive-expression

  additive-expression:
  • multiplicative-expression additive-expression + multiplicative-expression additive-expression - multiplicative-expression
  multiplicative-expression:
  • multiplicative-expression * cast-expression multiplicative-expression / cast-expression multiplicative-expression % cast-expression
  cast-expression:
  • unary expression (type-name) cast-expression
  unary-expression:
  • postfix expression ++unary expression --unary expression unary-operator cast-expression sizeof unary-expression sizeof (type-name)
  unary operator: one of

  • & * + - ~ !

  postfix-expression:
  • primary-expression postfix-expression[expression] postfix-expression(argument-expression-listopt) postfix-expression.identifier

    postfix-expression->+identifier postfix-expression++ postfix-expression--

  primary-expression:
  • identifier constant string (expression)
  argument-expression-list:
  • assignment-expression assignment-expression-list , assignment-expression
  constant:
  • integer-constant character-constant floating-constant enumeration-constant

The following grammar for the preprocessor summarizes the structure of control lines, but is not suitable for mechanized parsing. It includes the symbol text, which means ordinary program text, non-conditional preprocessor control lines, or complete preprocessor conditional instructions.

• control-line:
  • # define identifier token-sequence # define identifier(identifier, ... , identifier) token-sequence # undef identifier

    # include <filename> # include "filename" # line constant "filename" # line constant # error token-sequenceopt # pragma token-sequenceopt # preprocessor-conditional

  preprocessor-conditional:
  • if-line text elif-parts else-partopt #endif
  if-line:
  • # if constant-expression # ifdef identifier # ifndef identifier
  elif-parts:
  • elif-line text elif-partsopt
  elif-line:
  • # elif constant-expression
  else-part:
  • else-line text
  else-line:
  • #else