loading
语法分析子流程图：
3.程序代码实现
整个词法以及语法的程序设计在一个工程里面，一共包含了8个文件，分别为main.cpp、parse.cpp、scan.cpp、util.cpp、scan.h、util.h、 globals.h、parse.h,其中scan.cpp和scan.h为词法分析程序。
以下仅列出各个文件中的核心代码：
Main.cpp
#include \
#define NO_PARSE FALSE #include \#if NO_PARSE #include \#else
#include \#endif
int lineno=0; FILE * source; FILE * listing; FILE * code;
int EchoSource = TRUE;
int TraceScan=TRUE; int TraceParse=TRUE; int Error = FALSE;
int main(int argc,char * argv[]) {
TreeNode * syntaxTree; char pgm[120]; scanf(\ source=fopen(pgm,\ if(source==NULL)
{
fprintf(stderr,\exit(1);
} listing = stdout; fprintf(listing,\TION: %s\\n\#if NO_PARSE while(getToken()!=ENDFILE); #else
syntaxTree = parse(); if(TraceParse){ fprintf(listing,\ printTree(syntaxTree); } #endif fclose(source); return 0; }
Parse.cpp
#include \#include \#include \#include \
static TokenType token; /* holds current token */
/* function prototypes for recursive calls */ static TreeNode * declaration_list(void); static TreeNode * declaration(void); static TreeNode * params(void); static TreeNode * param_list(void); static TreeNode * param(void);
static TreeNode * compound_stmt(void); static TreeNode * local_declarations(void); static TreeNode * statement_list(void); static TreeNode * statement(void);
static TreeNode * expression_stmt(void); static TreeNode * if_stmt(void); static TreeNode * while_stmt(void); static TreeNode * return_stmt(void); static TreeNode * expression(void); static TreeNode * var(void);
static TreeNode * simple_exp(void);
static TreeNode * additive_expression(void); static TreeNode * term(void); static TreeNode * factor(void);
static TreeNode * args(void); static TreeNode * arg_list(void);
static void syntaxError(char * message) { fprintf(listing,\
fprintf(listing,\Error = TRUE; }
/*判断读取的字符*/
static void match(TokenType expected) {
if(token==expected) {
token=getToken( ); }
else {
syntaxError(\
printToken(token,tokenString);
fprintf(listing,\ \ } }
/*进行语法分析，构建语法树*/ TreeNode * declaration_list(void) { TreeNode * t= declaration(); TreeNode * p= t; while ((token==INT) || (token==VOID) ) {
TreeNode *q = declaration(); if (q!=NULL) { if (t==NULL) t = p = q; }
else /* now p cannot be NULL either */ { p->sibling = q; p = q; }
} return t; }
TreeNode * declaration(void) { TreeNode * t = NULL; switch (token) {
case VOID : case INT :
t = newStmtNode(DecK); if(token == INT) t->type =Integer; else
t->type = Void; match(token); switch (token) {