globals.h

<compiler construction principles and practice>书中定义的tiny语言编译器。

#include<stdlib.h>
#include<ctype.h>
#include<string.h>

extern int lineno = 0;
//int Error = 0;
typedef enum 
{
	ENDFILE,ERROR,
    IF,THEN,ELSE,END,REPEAT,UNTIL,READ,WRITE,
    ID,NUM,
    ASSIGN,EQ,LT,PLUS,MINUS,TIMES,OVER,LPAREN,RPAREN,SEMI
} TokenType;

void printToken( TokenType token, const char* tokenString )
{ switch (token)
  { case IF:
    case THEN:
    case ELSE:
    case END:
    case REPEAT:
    case UNTIL:
    case READ:
    case WRITE:
		cout << "reserved word:" << tokenString << endl;
      break;
	case ASSIGN:  cout << ":=" << endl;break;
    case LT: cout << "<" << endl; break;
    case EQ:  cout << "=" << endl; break;
    case LPAREN: cout << "(" << endl; break;
    case RPAREN: cout << ")" << endl; break;
    case SEMI: cout << ";" << endl; break;
    case PLUS: cout << "+" << endl; break;
    case MINUS:cout << "-" << endl; break;
    case TIMES:  cout << "*" << endl; break;
    case OVER:  cout << "/" << endl; break;
    case ENDFILE: cout << "EOF" << endl; break;
    case NUM:
      	cout << "NUM, val= " << tokenString << endl;
      break;
    case ID:
      	cout << "ID, name= " << tokenString << endl;
      break;
    case ERROR:
     	cout << "ERROR: " << tokenString << endl; 
      break;
    default: 
		cout << "Unknown token: "<< token << endl;
  }
}


typedef enum {StmtK,ExpK} NodeKind;
typedef enum {IfK,RepeatK,AssignK,ReadK,WriteK} StmtKind;
typedef enum {OpK,ConstK,IdK} ExpKind;

typedef enum {Void,Integer,Boolean} ExpType;

static int indentno = 0;

#define INDENT indentno+=2
#define UNINDENT indentno-=2

static void printSpaces(void)
{ int i;
  for (i=0;i<indentno;i++)
    cout<<"  ";
  cout<<"---- ";
}

char* CopyString(char* s)
{
	char *t;
	if(s==NULL) return NULL;
	t = new char[strlen(s)+1];
	if(t==NULL)
		cout<<"Out of memory error at line "<<lineno<<endl;
	else 
		strcpy(t,s);
	return t;
}

class Parse;
class TreeNode
{
	
public:
	TreeNode* child[3];
	TreeNode* sibling;

    int linenos;
	NodeKind nodekind;
	union { StmtKind stmt; ExpKind exp;} kind;
    union { TokenType op;
             int val;
             char * name; } attr;
     ExpType type;
	 TreeNode* NewStmtNode(StmtKind);
	 TreeNode * NewExpNode(ExpKind);
	 void printTree( TreeNode * );
};


TreeNode* TreeNode::NewStmtNode(StmtKind kind)
{ TreeNode * t = (TreeNode *) malloc(sizeof(TreeNode));
  int i;
  if (t==NULL)
	  cout<<"Out of memory error at line "<<lineno<<endl;
  else {
    for (i=0;i<3;i++) t->child[i] = NULL;
    t->sibling = NULL;
    t->nodekind = StmtK;
    t->kind.stmt = kind;
    t->linenos = lineno;
  }
  return t;
}


TreeNode* TreeNode::NewExpNode(ExpKind kind)
{ TreeNode * t = (TreeNode *) malloc(sizeof(TreeNode));
  int i;
  if (t==NULL)
	  cout<<"Out of memory error at line "<<lineno<<endl;
   else {
    for (i=0;i<3;i++) t->child[i] = NULL;
    t->sibling = NULL;
    t->nodekind = ExpK;
    t->kind.exp = kind;
    t->linenos = lineno;
    t->type = Void;
  }
  return t;
}


void TreeNode::printTree(TreeNode* tree)
{ int i;
  INDENT;
  while (tree != NULL) {
    printSpaces();
    if (tree->nodekind==StmtK)
    { switch (tree->kind.stmt) {
        case IfK:
			cout<<"If\n";
            break;
        case RepeatK:
			cout<<"Repeat\n";
            break;
        case AssignK:
			cout<<"Assign to: "<<tree->attr.name<<endl;
            break;
        case ReadK:
			cout<<"Read: "<<tree->attr.name<<endl;
            break;
        case WriteK:
			cout<<"Write\n";
            break;
        default:
			cout<<"Unknown ExpNode kind\n";
            break;
      }
    }
    else if (tree->nodekind==ExpK)
    { switch (tree->kind.exp) {
        case OpK:
			cout<<"Op: ";
            printToken(tree->attr.op,"\0");
            break;
        case ConstK:
			cout<<"Const: "<<tree->attr.val<<endl;
            break;
        case IdK:
			cout<<"Id: "<<tree->attr.name<<endl;
          break;
        default:
          cout<<"Unkown ExpNode kind\n";
          break;
      }
    }
    else cout<<"Unkown node kind\n";
    for (i=0;i<3;i++)
         printTree(tree->child[i]);
    tree = tree->sibling;
  }
  UNINDENT;
}