文法的改进

<program>-><external_declaration> | <program> <external_declaration>

<external_declaration> -><function_definition> | <declaration>

<function_definition> -><type_specifier> <declarator> <compound_statement>

<type_specifier>->void | char | int | float

<declarator>-><pointer direct_declarator> | <direct_declarator>

<Pointer>->'*'| '*' pointer

<direct_declarator>-><IDENTIFIER> |<direct_declarator’[‘ ‘]’>
|<direct_declarator ’[’ constant_expression ’]’>
| <identifier '(' parameter_list ')'>
| <IDENTIFIER '(' ')'>|<direct_declarator ‘,’ identifier_list>

<identifier_list>-><: IDENTIFIER>| <identifier_list ',' IDENTIFIER>

<constant_expression>-><conditional_expression>

<parameter_list>-><parameter_declaration>| <parameter_list> <','> <parameter_declaration>

<parameter_declaration>-><declaration_specifiers><IDENTIFIER>

<compound_statement>-><'{'< >'}'> | <'{'><statement_list><'}'>| <'{'><declaration_list statement_list ><'}'

<declaration_list>-><declaration>| <declaration_list><declaration>

<Declaration>-><init_declarator>| <init_declarator_list>< ','> <init_declarator>

<init_declarator>-><declarator>| <declarator> <'='> <initializer>

<Initializer >-><assignment_expression>| <'{'>< initializer_list>< '}>' |< '{'>< initializer_list>< ','> < '}'>

<initializer_program_list>-><initializer_program>| <initializer_program_list>< ','> <initializer_program>

<statement_list>-><statement>| <statement_list> <statement>

<Statement >->| <compound_statement> | <expression_statement> | <selection_statement> | <iteration_statement> | <jump_statement>

<expression_statement> -> < ';'> | <expression>< ';'>

<selection_statement> -> <:>< IF>< '('>< expression ><')'> <statement>
| <if> <'('>< expression ><')'> <statement><else> <statement>

<iteration_statement>-><while>< '('>< expression ><')'>< statement>
| <for> <'('>< expression_statement>< expression_statement>< ')'>< statement>
| <for> <'('>< expression_statement>< expression_statement>< expression ><')'>< statement>

<jump_statement>-> | CONTINUE< ';'> | BREAK< ';'> | RETURN <';'> | RETURN <expression> <';'>

<expression>-> <: ><assignment_expression> | <expression> <','> <assignment_expression>

<assignment_expression>-><conditional_expression>| <unary_expression>< assignment_operator>< assignment_expression>

<conditional_expression >-> <logical_or_expression>
| <logical_or_expression>< '?'>< expression ><':'>< conditional_expression>

<logical_or_expression >->< logical_and_expression> | <logical_or_expression> OR_OP <logical_and_expression>

<logical_and_expression> -> <:>< inclusive_or_expression> | <logical_and_expression> AND_OP <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 >EQ_OP <relational_expression> | <equality_expression> NE_OP <relational_expression>

<relational_expression><:> <shift_expression> | <relational_expression> <'><<><'> <shift_expression>

| <relational_expression '>' shift_expression>| <relational_expression LE_OP shift_expression>| <relational_expression GE_OP shift_expression>

<shift_expression>-> <:>< additive_expression> | <shift_expression LEFT_OP additive_expression> | <shift_expression RIGHT_OP additive_expression>

<additive_expression>-><:> <multiplicative_expression>
| <additive_expression> <'+'> <multiplicative_expression>
| <additive_expression> <'-'> <multiplicative_expression>

<multiplicative_expression> -> <:> <cast_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>
| <INC_OP unary_expression>
| <DEC_OP unary_expression>
| <unary_operator>< cast_expression>
| <SIZEOF unary_expression>
| <SIZEOF> '('>< type_name ><')'>

<postfix_expression >-><:> <primary_expression>
|< postfix_expression> <'['>< expression ><']'>
| <postfix_expression ><'('>< ')'>
| <postfix_expression '(' argument_expression_list ')'>
| <postfix_expression '.' IDENTIFIER>
| <postfix_expression PTR_OP IDENTIFIER>
| <postfix_expression INC_OP>
| <postfix_expression DEC_OP>

<primary_expression>->IDENTIFIER | CONSTANT | STRING_LITERAL | <'('>< expression ><')'>

<argument_expression_list>-> < :>< assignment_expression> | <argument_expression_list> <','> <assignment_expression>

<unary_operator>-> <:>< '&'> | <'*'> | <'+'> | <'-'>| <'~'> | <'!'>

<storage_class_specifier >-> TYPEDEF | EXTERN | STATIC | AUTO | REGISTER

<struct_or_union_specifier> ->< :>< struct_or_union IDENTIFIER>< '{'>< struct_declaration_list>< '}'>
| <struct_or_union ><'{' ><struct_declaration_list>< '}'>
| <struct_or_union> IDENTIFIER

<struct_or_union>-> <: >STRUCT | UNION

<struct_declaration_list> -> <:>< struct_declaration> | <struct_declaration_list ><struct_declaration>

<struct_declaration> -><:>< specifier_qualifier_list>< struct_declarator_list>< ';'>

<specifier_qualifier_list >-> < type_specifier>< specifier_qualifier_list>
| <type_specifier>
| <type_qualifier ><specifier_qualifier_list>
| <type_qualifier>

<struct_declarator_list>-><struct_declarator>
| <struct_declarator_list>< ','>< struct_declarator>

<struct_declarator>-> <:>< declarator> |< ':'>< constant_expression>
| <declarator ><':'> <constant_expression>

<enum_specifier >-> < ENUM '{' enumerator_list '}'>
| <ENUM IDENTIFIER '{' enumerator_list '}'>
| ENUM IDENTIFIER

<enumerator_list >-> enumerator | enumerator_list <','> enumerator

<Enumerator >->IDENTIFIER | IDENTIFIER <'='> <constant_expression>

<type_qualifier >->CONST | VOLATILE

<type_qualifier_list>-> <type_qualifier> | <type_qualifier_list> <type_qualifier>

<parameter_type_list>-> <parameter_list> | <parameter_list ><','> ELLIPSIS

<parameter_list>-> <:>< parameter_declaration> | <parameter_list>< ','>< parameter_declaration>

<type_name>->< specifier_qualifier_list> | <specifier_qualifier_list>< abstract_declarator>

<abstract_declarator>-> pointer | <direct_abstract_declarator> | <pointer direct_abstract_declarator>