說明：

????以下內容基于ISO C89標準。其中，一行開頭的 | 表示或者的意思，[]里面的內容是可選的。不是行頭的 | 都是 字符 '|' 的意思，如果文法中用到字符 [ ]，則使用 '[' 和 ']'表示。

????該文法適合用來理解C語言的文法，但不適合用來寫編譯器。因為該文法中有大量左遞歸和左公因子，且是二義性的，總共有 500 行左右，最重要的一點是它不是上下文無關的，所以編譯原理中的LL分析法和LR分析法都派不上用場 T_T。

????也就是說，對該文法做一些特殊處理才能夠用于C編譯器的開發(fā)。

????該文法的開始符號是： 翻譯單元?translation_unit。

????純手打。

C89文法

一、詞法

1. 單詞, 預處理單詞

token :?

? ? keyword?

? ? identifier

? ? constant

? ? string_literal

? ? operator

? ? punctuator

preprocessing_token :?

? ? header_name?

? ? identifier

? ? pp_number

? ? character_constant

? ? string_literal

? ? operator

? ? punctuator

? ? 不在上述范圍內的任一非空白符

2. 關鍵字

keyword:

auto ? ? double ? ? int ? ? ? ? struct

break ? ? else? ? ? ? long ? ? switch

case? ? ? ? enum? ? ? ? register typedef

char ? ? extern ? ? return? union

const ? ? float ? ? short ? ? unsigned

for ? ? signed ? ? void default

goto ? ? sizeof ? ? volatile do

if ? ? ? ? static ? ? while? ? ? ?continue

3. 標識符

identifier ：

? ? nodigit

? ? identifier nodigit

? ? identifier digit

nodigit :?

? ? _ a b c d e f g h i j k l m n o p q r s t

? ? u v w x y z A B C D E F G H I J K L M N O

? ? P Q R S T U V W X Y Z

digit :

? ? 0 1 2 3 4 5 6 7 8 9

4. 常量

constant :

? ? floating_constant

? ? | integer_constant

? ? | enumeration_constant

? ? | character_constant

floating_constant :

? ? fractional_constant [exponent_part] [floating_suffix]

| digit_sequence exponent_part [floating_suffix]

fractional_constant :?

[digit_sequence] . digit_sequence

? ? | digit_sequence

exponent_part:

? ? e [sign] digit_sequence

? ? | E [sign] digit_sequence

sign:

? ? + | -

digit_sequence:

? ? digit

? ? | digit_sequence digit

floating_suffix:

? ? f | l | F | L

integer_constant:

? ? decimal_constant [integer_suffix]

? ? | octal_contant [integer_suffix]

? ? | hexadecimal_constant [integer_suffix]

decimal_constant:

? ? nonzero_digit

? ? | decimal_constant digit

octal_contant:

? ? 0

? ? | octal_contant octal_digit

hexadecimal_constant:

? ? 0x hexadecimal_digit

? ? | 0X hexadecimal_digit

? ? | hexadecimal_constant hexadecimal_digit

nonzero_digit:

? ? 1 2 3 4 5 6 7 8 9

octal_digit:

? ? 0 1 2 3 4 5 6 7

hexadecimal_digit:

? ? ?0 1 2 3 4? 5 6 7 8 9

? ? ?a b c d e f g

? ? ?A B C D E F G

integer_suffix:

? ? unsigned_suffix [long_suffix]

? ? | long_suffix [unsigned_suffix]

unsigned_suffix :

? ? u | U

long_suffix :

? ? l | L

enumeration_constant :

? ? identifier

character_constant:

? ? ' c_char_sequence '

? ? | L' c_char_sequence '

c_char_sequence:

? ? c_char

? ? | c_char_sequence c_char

c_char:

? ? 源字符集中除 單引號 '，右反斜線 \，換行符 \n 外的所有字符

? ? | escape_sequence

escape_sequence:

? ? simple_escape_sequence

? ? | octal_escape_sequence

? ? | hexadecimal_escape_sequence

simple_escape_sequence: \' | \" | \? | \\ | \a | \b | \f | \n | \r | \t | \v

octal_escape_sequence:

? ? \ octal_digit

? ? | \ octal_digit octal_digit

? ? | \ octal_digit octal_digit octal_digit

hexadecimal_escape_sequence:

? ? \x hexadecimal_digit

? ? | hexadecimal_escape_sequence hexadecimal_digit

5. 字符串字面量

string_literal:

? ? " [s_char_sequence] "

? ? | L" [s_char_sequence] "

s_char_sequence:

? ? s_char

? ? | s_char_sequence s_char

s_char:

? ? 源字符集中除 雙引號 "，右反斜線 \，換行符 \n 外的所有字符

? ? | escape_sequence

6. 運算符

operator:

? ? [ ] ( ) . -> ++ -- & * + - ! sizeof / % << >> < > <= >= != ^ | && ||

? ? = *= /= %= += -= <<= >>= &= ^= |= , # ##

7. 標點符號

punctuator:

? ? [ ] ( ) { } * , : = ; ... #

8. 標頭名

header_name:

? ? < h_char_sequence >

? ? " q_char_sequence "

h_char_sequence:

? ? h_char

? ? | h_char_sequence h_char

h_char:

? ? 源字符集中除 換行符 \n ， 大于號 > 外的所有字符

q_char_sequence:

? ? q_char

? ? | q_char_sequence q_char

q_char:

? ? 源字符集中除 換行符 \n ， 雙引號" 外的所有字符

9. 預處理數(shù)字

pp_number:

? ? digit

? ? | .digit

? ? | pp_number digit

? ? | pp_number nonzero_digit

? ? | pp_number e sign

? ? | pp_number E sign

? ? | pp_number .

二、語法

1. 表達式

primary_expression:

? ? identifier

? ? | constant

? ? | string_literal

? ? | (expression)

postfix_expression:

? ? primary_expression

? ? | postfix_expression '[' expression ']'

? ? | postfix_expression ([argument_expression_list])

? ? | postfix_expression . identifier

? ? | postfix_expression -> identifier

? ? | postfix_expression ++

? ? | postfix_expression --

argument_expression_list:

? ? assignment_expression

? ? | assignmant_expression_list , assignment_expression

unary_expression:

? ? postfix_expression

? ? | ++ unary_expression

? ? | -- unary_expression

? ? | unary_operator cast_expression

? ? | sizeof unary_expression

? ? | sizeof (type_name)

unary_operator:

? ? & * + - ~ !

cast_expression:

? ? unary_expression

? ? | (type_name) cast_expression

multiplicative_expression:

? ? cast_expression

? ? | multiplicative_expression * cast_expression

? ? | multiplicative_expression / cast_expression

? ? | multiplicative_expression % cast_expression

|?

addtive_expression:

? ? multiplicative_expression

? ? | addtive_expression + multiplicative_expression

? ? | addtive_expression - multiplicative_expression

shift_expression:

? ? addtive_expression

? ? | shift_expression << addtive_expression

? ? | shift_expression >> addtive_expression

relational_expression:

? ? shift_expression

? ? | relational_expression < shift_expression

? ? | relational_expression <= shift_expression

? ? | relational_expression > shift_expression

? ? | relational_expression >= shift_expression

equality_expression:

? ? relational_expression

? ? | equality_expression == relational_expression

? ? | equality_expression != relational_expression

and_expression:

? ? equality_expression

? ? | and_expression & relational_expression

exclusive_or_expression:

? ? and_expression

? ? | exclusive_or_expression ^ and_expression

inclusive_or_expression:

? ? exclusive_or_expression

? ? | inclusive_or_expression | exclusive_or_expression

logical_and_expression:

? ? inclusive_or_expression

? ? | logical_and_expression && inclusive_or_expression

logical_or_expression:

? ? logical_and_expression

? ? | logical_or_expression || logical_and_expression

conditional_expression:

? ? logical_or_expression?

? ? | logical_or_expression ? expression : conditional_expression

assignment_expression:

? ? conditional_expression

? ? | unary_expression assignment_operator assignment_expression

assignment_operator:

? ? = *= /= %= += -= <<= >>= &= ^= |=

expression:

? ? assignment_expression

? ? | expression assignment_expression

constant_expression:

? ? conditional_expression

2. 聲明

declaration:

? ? declaration_specifier [init_declaratior_list] ;

declaration_specifier:

? ? storage_class_specifier [declaration_specifier]

? ? | type_specifer [declaration_specifier]

? ? | type_qualifier [declaration_specifier]

init_declaratior_list:

? ? init_declarator

? ? | init_declaratior_list , init_declarator

init_declarator:

? ? declarator

? ? | declarator = initializer

storage_class_specifier:

? ? typedef

? ? | extern

? ? | static

? ? | auto

? ? | register

type_specifer:

? ? void

? ? | char

? ? | short

? ? | int

? ? | long

? ? | float

? ? | double

? ? | signed

? ? | unsigned

? ? | struct_or_union_specifer

? ? | enum_specifier

? ? | typedef_name

struct_or_union_specifer:

? ? struct_or_union [identifier] { 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_specifer [specifier_qualifier_list]

? ? | type_qualifier [specifier_qualifier_list]

struct_declarator_list:

? ? struct_declarator

? ? | struct_declarator_list, struct_declarator

struct_declarator:

? ? declarator

? ? | [declarator] : constant_expression

enum_specifier:

? ? enum [identifier] {enumerator_list}

? ? | enum identifier

enumerator_list:

? ? enumerator

? ? | enumerator_list, enumerator

enumerator:

? ? enumeration_constant

? ? | enumeration_constant = constant_expression

enumeration_constant:

? ? identifier

type_qualifier:

? ? const

? ? | volatile

parameter_declaration:

? ? declaration_specifier declarator

? ? | declaration_specifier [abstract_declarator]

declarator:

? ? [pointer] direct_declarator

abstract_declarator:

? ? pointer

? ? | [pointer] direct_abstract_delarator

direct_declarator:

? ? identifier

? ? | (declarator)

? ? | direct_declarator '[' [ constant_expression ] ']'

? ? | direct_declarator (parameter_type_list)

? ? | direct_declarator ( [identifier_list] )

direct_abstract_delarator:

? ?(abstract_declarator)

? ?| [direct_abstract_delarator] '[' [constant_expression] ']'

? ?| [direct_abstract_delarator] ( [parameter_type_list] )

pointer:

? ? * [type_qualifier_list]

? ? | * [type_qualifier_list] 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

identifier_list:

? ? identifier

? ? | identifier_list, identifier

type_name:

? ? specifier_qualifier_list [abstract_declarator]

specifier_qualifier_list:

? ? type_specifer [specifier_qualifier_list]

? ? | type_qualifier [specifier_qualifier_list]

typedef_name:

? ? identifier

initializer:

? ? assignment_expression

? ? | {initializer_list}

? ? | {initializer_list,}

initializer_list:

? ? initializer

? ? | initializer_list, initializer

3. 語句

statement:

? ? labeled_statement

? ? | compound_statement

? ? | expression_statement

? ? | selection_statement

? ? | iteration_statement

? ? | jump_statement

labeled_statement:

? ? identifier : statement

? ? | case constant_expression : statement

? ? | default : statement

compound_statement:

? ? {[declaration_list] [statement_list]}

declaration_list:

? ? declaration

? ? | declaration_list declaration

statement_list:

? ? statement

? ? | statement_list statement

expression_statement:

? ? [expression] ;

selection_statement:

? ? if(expression) statement

? ? | if(expression) statement else statement

? ? | switch(expression) statement

iteration_statement:

? ? while(expression) statement

? ? | do statement while(expression) ;

? ? | for([expression] ; [expression] ; [expression]) statement

jump_statement:

? ? goto identifier ;

? ? | continue ;

? ? | break ;

? ? | return [expression] ;

4. 外部定義

translation_unit:

? ? external_declaration

? ? | translation_unit external_declaration

external_declaration:

? ? functionn_definition

? ? | declaration

functionn_definition:

? ? | [declaration_specifier] declarator [declaration_list] compound_statement

6. 預處理命令

preprocessing_file:

? ? [group]

group:

? ? gruop_part

? ? | group gruop_part

gruop_part:

? ? [pp_tokens] new_line

? ? | if_section

? ? | control_line

if_section:

? ? if_group [elif_groups] [else_group] endif_line

if_group:

? ? # if constant_expression new_line [group]

? ? | # ifdef identifier new_line [group]

? ? | #ifndef identifier new_line [group]

elif_groups:

? ? elif_group

? ? | elif_groups elif_group

elif_group:

? ? # elif constant_expression new_line [group]

else_group:

? ? # else new_line [group]

endif_line:

? ? # endif new_line

control_line:

? ? # include pp_tokens new_line

? ? | # define identifier replacement_list new_line

? ? | # define identifier lparen [identifier_list] ) replacement_list new_line

? ? | # undef identifier new_line

? ? | # line pp_tokens new_line

? ? | # error [pp_tokens] new_line

? ? | # pragma [pp_tokens] new_line

? ? | # new_line

lparen:

? ? 前面沒有空白符的左括號(

replacement_list:

? ? [pp_tokens]

pp_tokens:

? ? preprocessing_token

? ? | pp_tokens preprocessing_token

new_line:

? ? 換行符\n