TCPL/A.13_Grammar

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 &lt; shift-expression
  relational-expression &gt; shift-expression
  relational-expression &lt;= shift-expression
  relational-expression &gt;= shift-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-&gt;+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 &lt;filename&gt;
  # 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