Token);
}
return currentToken;
}*/
它的yacc文件是这么写的，
/***********************************/
/* File: cmm.y */
/* Bison grammar file about CMM */
/* CMM Interpreter Construction */
/***********************************/
/*预计有1个移进/归约冲突*/
%expect 1
%{
#include "globals.h"
#include "util.h"
#include "scan.h"
#include "parse.h"
static TreeNode * savedTree; /* stores syntax tree for later return */
%}
%union{
struct treeNode * node;
int intval;
double realval;
char * idName;
int binaryOperator;
int dataType;
}
%token
INT_VALUE
%token
REAL_VALUE %token
ID %token
INT REAL BOOL /* 优先级声明 */ %right ASSIGN %left PLUS SUB %left MUL DIV %nonassoc
REL_OP %nonassoc UMINUS /* 声明文法中用到的tokens */ %token IF ELSE WHILE READ WRITE MAIN %token LPAREN RPAREN SEMI LBRACE RBRACE LBRACKET RBRACKET COMMA %token ASSIGN %token NEWLINE ERROR %type
stmt_list stmt %type
if_stmt decl_stmt compound_stmt while_stmt assign_stmt read_stmt write_stmt %type
exp factor bin_exp %type
type_spec %start program %% /* CMM文法 */ program : stmt_list { savedTree = $1;} ; stmt_list : { $$ = NULL; } | stmt_list stmt { TreeNode * t = $1; if (t != NULL) { while (t->sibling != NULL){ t = t->sibling;} t->sibling = $2; $$ = $1; } else $$ = $2; } ; stmt : if_stmt { $$ = $1; } | decl_stmt SEMI { $$ = $1; } | compound_stmt { $$ = $1; } | while_stmt { $$ = $1; } | assign_stmt SEMI { $$ = $1; } | read_stmt SEMI { $$ = $1; } | write_stmt SEMI { $$ = $1; } | error { $$ = NULL; } ; compound_stmt : LBRACE stmt_list RBRACE { $$ = newStmtNode(CompoundK); $$->child[0] = $2; $$->lineno = lineno; } ; decl_stmt : type_spec ID { $$ = newStmtNode(DeclK); $$->attr.name = $2; /* 数组长度为0代表非数组 */ $$->arrayLength = 0; $$->type = $1; $$->lineno = lineno; } | type_spec ID LBRACKET INT_VALUE RBRACKET { $$ = newStmtNode(DeclK); $$->attr.name = $2; $$->arrayLength = $4; $$->type = $1; if($$->type == Int) { int int_array_temp[$4]; $$->array.intArray = int_array_temp; } else if($$->type == Real) { double real_array_temp[$4]; $$->array.realArray = real_array_temp; } $$->lineno = lineno; } ; type_spec : INT { $$ = $1; } | REAL { $$ = $1; } | BOOL { $$ = $1; } ; if_stmt : IF LPAREN bin_exp RPAREN stmt { $$ = newStmtNode(IfK); $$->child[0] = $3; $$->child[1] = $5; $$->child[2] = NULL; $$->lineno = lineno; } | IF LPAREN bin_exp RPAREN stmt ELSE stmt { $$ = newStmtNode(IfK); $$->child[0] = $3; $$->child[1] = $5; $$->child[2] = $7; $$->lineno = lineno; } ; while_stmt : WHILE LPAREN bin_exp RPAREN stmt { $$ = newStmtNode(WhileK); $$->child[0] = $3; $$->child[1] = $5; $$->lineno = lineno; } ; assign_stmt : ID ASSIGN exp { $$ = newStmtNode(AssignK); $$->attr.name = $1; $$->child[0] = $3; $$->child[1] = NULL; $$->lineno = lineno; } | ID LBRACKET exp RBRACKET ASSIGN exp { $$ = newStmtNode(AssignK); $$->attr.name = $1; /* child[1]不为NULL 表示引用的变量是一个数组元素 */ /* child[0] 是数组元素的下标 */ $$->child[0] = $3; $$->child[1] = $6; $$->lineno = lineno; } ; read_stmt : READ LPAREN ID RPAREN { $$ = newStmtNode(ReadK); $$->attr.name = $3; $$->child[0] = NULL; $$->lineno = lineno; } | READ LPAREN ID LBRACKET exp RBRACKET RPAREN { $$ = newStmtNode(ReadK); $$->attr.name = $3; $$->child[0] = $5; $$->lineno = lineno; } ; write_stmt : WRITE LPAREN exp RPAREN { $$ = newStmtNode(WriteK); $$->child[0] = $3; $$->lineno = lineno; } ; exp : factor { $$ = $1; } | bi