一款开源C语言编译器源码解析

//keywords
TOKEN(TK_AUTO,      "auto")
TOKEN(TK_EXTERN,    "extern")
TOKEN(TK_REGISTER,  "register")
TOKEN(TK_STATIC,    "static")
TOKEN(TK_TYPEDEF,   "typedef")
TOKEN(TK_CONST,     "const")
TOKEN(TK_VOLATILE,  "volatile")
TOKEN(TK_SIGNED,    "signed")
TOKEN(TK_UNSIGNED,  "unsigned")
TOKEN(TK_SHORT,     "short")
TOKEN(TK_LONG,      "long")
TOKEN(TK_CHAR,      "char")
TOKEN(TK_INT,       "int")
TOKEN(TK_INT64,     "__int64")
TOKEN(TK_FLOAT,     "float")
TOKEN(TK_DOUBLE,    "double")
TOKEN(TK_ENUM,      "enum")
TOKEN(TK_STRUCT,    "struct")
TOKEN(TK_UNION,     "union")
TOKEN(TK_VOID,      "void")
TOKEN(TK_BREAK,     "break")
TOKEN(TK_CASE,      "case")
TOKEN(TK_CONTINUE,  "continue")
TOKEN(TK_DEFAULT,   "default")
TOKEN(TK_DO,        "do")
TOKEN(TK_ELSE,      "else")
TOKEN(TK_FOR,       "for")
TOKEN(TK_GOTO,      "goto")
TOKEN(TK_IF,        "if")
TOKEN(TK_RETURN,    "return")
TOKEN(TK_SWITCH,    "switch")
TOKEN(TK_WHILE,     "while")
TOKEN(TK_SIZEOF,    "sizeof")

//identifier
TOKEN(TK_ID,        "ID")

//constant
TOKEN(TK_INTCONST,     "int")
TOKEN(TK_UINTCONST,    "unsigned int")
TOKEN(TK_LONGCONST,    "long")
TOKEN(TK_ULONGCONST,   "unsigned long")
TOKEN(TK_LLONGCONST,   "long long")
TOKEN(TK_ULLONGCONST,  "unsigned long long")
TOKEN(TK_FLOATCONST,   "float")
TOKEN(TK_DOUBLECONST,  "double")
TOKEN(TK_LDOUBLECONST, "long double")
TOKEN(TK_STRING,       "STR")
TOKEN(TK_WIDESTRING,   "WSTR")

//operators
TOKEN(TK_COMMA,         ",")
TOKEN(TK_QUESTION,      "?")
TOKEN(TK_COLON,         ":")
TOKEN(TK_ASSIGN,        "=")
TOKEN(TK_BITOR_ASSIGN,  "|=")
TOKEN(TK_BITXOR_ASSIGN, "^=")
TOKEN(TK_BITAND_ASSIGN, "&=")
TOKEN(TK_LSHIFT_ASSIGN, "<<=")
TOKEN(TK_RSHIFT_ASSIGN, ">>=")
TOKEN(TK_ADD_ASSIGN,    "+=")
TOKEN(TK_SUB_ASSIGN,    "-=")
TOKEN(TK_MUL_ASSIGN,    "*=")
TOKEN(TK_DIV_ASSIGN,    "/=")
TOKEN(TK_MOD_ASSIGN,    "%=")
TOKEN(TK_OR,            "||")
TOKEN(TK_AND,           "&&")
TOKEN(TK_BITOR,         "|")
TOKEN(TK_BITXOR,        "^")
TOKEN(TK_BITAND,        "&")
TOKEN(TK_EQUAL,         "==")
TOKEN(TK_UNEQUAL,       "!=")
TOKEN(TK_GREAT,         ">")
TOKEN(TK_LESS,          "<")
TOKEN(TK_GREAT_EQ,      ">=")
TOKEN(TK_LESS_EQ,       "<=")
TOKEN(TK_LSHIFT,        "<<")
TOKEN(TK_RSHIFT,        ">>")
TOKEN(TK_ADD,           "+")
TOKEN(TK_SUB,           "-")
TOKEN(TK_MUL,           "*")
TOKEN(TK_DIV,           "/")
TOKEN(TK_MOD,           "%")
TOKEN(TK_INC,           "++")
TOKEN(TK_DEC,           "--")
TOKEN(TK_NOT,           "!")
TOKEN(TK_COMP,          "~")
TOKEN(TK_DOT,           ".")
TOKEN(TK_POINTER,       "->")
TOKEN(TK_LPAREN,        "(")
TOKEN(TK_RPAREN,        ")")
TOKEN(TK_LBRACKET,      "[")
TOKEN(TK_RBRACKET,      "]")

//punctuators
TOKEN(TK_LBRACE,        "{")
TOKEN(TK_RBRACE,        "}")
TOKEN(TK_SEMICOLON,     ";")
TOKEN(TK_ELLIPSE,       "...")
TOKEN(TK_POUND,         "#")
TOKEN(TK_NEWLINE,       "\n")

TOKEN(TK_END,           "EOF")

static Scanner        Scanners[256];

#define NEXT_TOKEN  CurrentToken = GetNextToken();

###语法解析语法解析与词法分析一起执行，取一个token然后解析。

Decl.c
transUnit = ParseTranslationUnit(file);

ParseTranslationUnit

	ParseExternalDeclaration//解析外部声明

		ParseCommonHeader//各种声明的共同部分

			ParseDeclarationSpecifiers//处理类型限定符(const)、说明符(int)、存储地说明符(auto)

			ParseInitDeclarator

				ParseDeclarator

				ParsePostfixDeclarator

					ParseDirectDeclarator

		GetFunctionDeclarator

		ParseCompoundStatement//如果是函数定义，解析函数的实现、

			ParseDeclaration

			ParseStatement

				ParseLabelStatement

				ParseCaseStatement

				ParseDefaultStatement

				ParseIfStatement

				ParseSwitchStatement

				ParseWhileStatement

				ParseDoStatement

				ParseForStatement

				ParseGotoStatement

				ParseContinueStatement

				ParseBreakStatement

				ParseReturnStatement

				ParseCompoundStatement

				ParseExpressionStatement

ParseExpression

/**
 *  assignment-expression:
 *      conditional-expression
 
 *      unary-expression assignment-operator assignment-expression
 *  assignment-operator:
 *      = *= /= %= += -= <<= >>= &= ^= |=
 *  There is a little twist here: the parser always treats the first nonterminal
 *  as a conditional expression.
 */	
	ParseAssignmentExpression

		ParseConditionalExpression

		ParseAssignmentExpression

ast节点结构
#define AST_NODE_COMMON   \
    int kind;             \节点类型
    struct astNode *next; \
    struct coord coord;

节点类型
enum nodeKind 
{ 
	NK_TranslationUnit,     NK_Function,           NK_Declaration,
	NK_TypeName,            NK_Specifiers,         NK_Token,				
	NK_TypedefName,         NK_EnumSpecifier,      NK_Enumerator,			
	NK_StructSpecifier,     NK_UnionSpecifier,     NK_StructDeclaration,	
	NK_StructDeclarator,    NK_PointerDeclarator,  NK_ArrayDeclarator,		
	NK_FunctionDeclarator,  NK_ParameterTypeList,  NK_ParameterDeclaration,
	NK_NameDeclarator,      NK_InitDeclarator,     NK_Initializer,
	
	NK_Expression,

	NK_ExpressionStatement, NK_LabelStatement,     NK_CaseStatement,		
	NK_DefaultStatement,    NK_IfStatement,        NK_SwitchStatement,		
	NK_WhileStatement,      NK_DoStatement,        NK_ForStatement,		
	NK_GotoStatement,       NK_BreakStatement,     NK_ContinueStatement,		
	NK_ReturnStatement,     NK_CompoundStatement
};

编译单元cpp
struct astTranslationUnit
{
	AST_NODE_COMMON
	AstNode extDecls;
};