chsh.h

一个类c++语言解释器

const int MAX_T_LEN  = 128;   // max token length
const int MAX_ID_LEN = 31;    // max identifier length
const int PROG_SIZE  = 10000; // max program size
const int NUM_PARAMS = 31;    // max number of parameters

// Enumeration of token types.
enum tok_types { UNDEFTT, DELIMITER, IDENTIFIER,
                 NUMBER, KEYWORD, TEMP, STRING, BLOCK };

// Enumeration of internal representation of tokens.
enum token_ireps { UNDEFTOK, ARG, CHAR, INT, SWITCH,
                   CASE, IF, ELSE, FOR, DO, WHILE, BREAK,
                   RETURN, COUT, CIN, END };

// Enumeration of two-character operators, such as <=.
enum double_ops { LT=1, LE, GT, GE, EQ, NE, LS, RS, INC, DEC };

// These are the constants used when throwing a
// syntax error exception.
//
// NOTE: SYNTAX is a generic error message used when
// nothing else seems appropriate.
enum error_msg
     { SYNTAX, NO_EXP, NOT_VAR, DUP_VAR, DUP_FUNC,
       SEMI_EXPECTED, UNBAL_BRACES, FUNC_UNDEF,
       TYPE_EXPECTED, RET_NOCALL, PAREN_EXPECTED,
       WHILE_EXPECTED, QUOTE_EXPECTED, DIV_BY_ZERO,
       BRACE_EXPECTED, COLON_EXPECTED };

extern char *prog;  // current location in source code
extern char *p_buf; // points to start of program buffer

extern char token[MAX_T_LEN+1]; // string version of token
extern tok_types token_type; // contains type of token
extern token_ireps tok; // internal representation of token

extern int ret_value; // function return value

extern bool breakfound; // true if break encountered

// Exception class for Mini C++.
class InterpExc {
  error_msg err;
public:
  InterpExc(error_msg e) { err = e; }
  error_msg get_err() { return err; }
};

// Interpreter prototypes.
void prescan();
void decl_global();
void call();
void putback();
void decl_local();
void exec_if();
void find_eob();
void exec_for();
void exec_switch();
void get_params();
void get_args();
void exec_while();
void exec_do();
void exec_cout();
void exec_cin();
void assign_var(char *var_name, int value);
bool load_program(char *p, char *fname);
int find_var(char *s);
void interp();
void func_ret();
char *find_func(char *name);
bool is_var(char *s);
token_ireps find_var_type(char *s);

// Parser prototypes.
void eval_exp(int &value);
void eval_exp0(int &value);
void eval_exp1(int &value);
void eval_exp2(int &value);
void eval_exp3(int &value);
void eval_exp4(int &value);
void eval_exp5(int &value);
void atom(int &value);
void sntx_err(error_msg error);
void putback();
bool isdelim(char c);
token_ireps look_up(char *s);
int find_var(char *s);
tok_types get_token();
int internal_func(char *s);
bool is_var(char *s);

// "Standard library" prototypes.
int call_getchar();
int call_putchar();
int call_abs();
int call_rand();