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bi.c
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/*
*文件功能：BASIC解释器
*历史来源：五字班方案二代码
*整合作者：赵哲晖
*整合时间：2018/05/09
*/
// A mini BASIC interpreter
// Statements: LET INPUT PRINT FOR(ENDFOR) IF-ELSE(ENDIF)
// Basic algebraic operation and logical operation
// Usage: bi filename
// A sample:
/*
PRINT "LINE = "
INPUT A
IF A < 10
FOR B = 1 TO A
FOR C = 1 TO A - B
PRINT " "
ENDFOR
FOR D = 1 TO 2*B-1
PRINT "*"
ENDFOR
PRINT "\n"
ENDFOR
ELSE
PRINT "NO\n"
ENDIF
*/
#include "types.h"
#include "stat.h"
#include "user.h"
// expression
typedef enum {var_null = 0, var_int, var_string} var_type;
typedef char STRING[128];
typedef struct
{
var_type type;
union
{
int i;
STRING s;
};
} VARIANT;
#define MEMORY_SIZE 26
VARIANT memory[MEMORY_SIZE];
typedef VARIANT OPERAND;
typedef enum
{
oper_lparen = 0, // (
oper_rparen, // )
oper_plus, // +
oper_minus, // -
oper_multiply, // *
oper_divide, // /
oper_mod, // %
oper_lt, // <
oper_gt, // >
oper_eq, // ==
oper_ne, // !=
oper_le, // <=
oper_ge, // >=
oper_and, // &
oper_or, // |
oper_not, // !
oper_min // bottom
} operator_type;
typedef enum {left2right, right2left} associativity;
typedef struct
{
int numbers; // operands
int icp; // priority
int isp; // priority
associativity ass;
operator_type oper;
} OPERATOR;
static const OPERATOR operators[] =
{
{2, 17, 1, left2right, oper_lparen},
{2, 17, 17, left2right, oper_rparen},
{2, 12, 12, left2right, oper_plus},
{2, 12, 12, left2right, oper_minus},
{2, 13, 13, left2right, oper_multiply},
{2, 13, 13, left2right, oper_divide},
{2, 13, 13, left2right, oper_mod},
{2, 10, 10, left2right, oper_lt},
{2, 10, 10, left2right, oper_gt},
{2, 9, 9, left2right, oper_eq},
{2, 9, 9, left2right, oper_ne},
{2, 10, 10, left2right, oper_le},
{2, 10, 10, left2right, oper_ge},
{2, 5, 5, left2right, oper_and},
{2, 4, 4, left2right, oper_or},
{1, 15, 15, right2left, oper_not},
{2, 0, 0, right2left, oper_min}
};
typedef enum {token_null = 0, token_operand, token_operator} token_type;
typedef struct
{
token_type type;
union
{
OPERAND var;
OPERATOR ator;
};
} TOKEN;
typedef struct tlist
{
TOKEN token;
struct tlist *next;
} TOKEN_LIST, *PTLIST;
char *e;
// grammar
typedef enum
{
key_null = 0,
key_let,
key_input,
key_print,
key_for,
key_endfor,
key_if,
key_else,
key_endif,
key_list,
key_goto,
key_while,// 5.22 new
key_wend //5.22 new
}keywords;
struct
{
int id;
int ln;
int target;
int step;
}stack_for[MEMORY_SIZE];
int top_for = -1;
struct
{
int id;
int ln;
int target;
int sign;
}stack_while[MEMORY_SIZE];
int top_while = -1;
// load
#define PROGRAM_SIZE 1000
typedef struct
{
int ln;
STRING line;
} CODE;
CODE code[PROGRAM_SIZE];
int cp;
int code_size;
// functions
// stack
PTLIST stack_ini();
void stack_push(PTLIST, TOKEN);
TOKEN stack_pop(PTLIST);
TOKEN stack_top(PTLIST);
void stack_free(PTLIST);
// expression
TOKEN next_token();
VARIANT eval(char *);
// grammar
keywords yacc(STRING);
void exec_input(STRING);
void exec_print(STRING);
void exec_for(STRING);
void exec_endfor(STRING);
void exec_if(STRING);
void exec_else(STRING);
void exec_endif(STRING);
void exec_let(STRING);
void exec_null(STRING);
void exec_list(STRING);
void exec_goto(STRING);
void exec_while(STRING);//5.22 new
void exec_wend(STRING);//5.22 new
// load
int isspace(char);
int isalpha(char);
int isdigit(char);
int isalnum(char);
char toupper(char);
char* _strstr(char*, char*);
char* _strcat(char*, char*);
int stricmp(char*, char*, int);
int readline(int, char*);
void load_program(char*);
void readCodeFromShell();
PTLIST
stack_ini()
{
PTLIST p;
p = (PTLIST)malloc(sizeof(TOKEN_LIST));
if(p == 0)
{
return 0;
}
else
{
p->next = 0;
return p;
}
}
void
stack_push(PTLIST st, TOKEN x)
{
PTLIST t;
t = (PTLIST)malloc(sizeof(TOKEN_LIST));
if(t == 0)
{
exit();
}
else
{
t->token = x;
t->next = st->next;
st->next = t;
}
}
TOKEN
stack_pop(PTLIST st)
{
PTLIST t;
TOKEN to;
t = st->next;
to = t->token;
st->next = t->next;
free(t);
return to;
}
TOKEN
stack_top(PTLIST st)
{
TOKEN t;
t.type = token_null;
if(st->next != 0)
{
t = (st->next)->token;
return t;
}
else
{
return t;
}
}
void
stack_free(PTLIST st)
{
while(st->next != 0)
{
stack_pop(st);
}
free(st);
}
// expression
TOKEN
next_token()
{
TOKEN token;
int i;
STRING str_t;
token.type = token_null;
while(*e && isspace(*e))
{
e++;
}
if(*e == '\0')
{
return token;
}
// string
if(*e == '"')
{
token.type = token_operand;
token.var.type = var_string;
e++;
for(i = 0; *e && *e != '"'; i++)
{
token.var.s[i] = *e;
e++;
}
token.var.s[i] = '\0';
e++;
}
// variable
else if(isalpha(e[0]) && !isalpha(e[1]))
{
token.type = token_operand;
token.var = memory[*e - 'A'];
e++;
if(token.var.type == var_null)
{
printf(1, "assignment error\n");
exit();
}
}
// digit
else if(isdigit(*e))
{
token.type = token_operand;
token.var.type = var_int;
for(i = 0; *e && isdigit(*e); i++)
{
str_t[i] = *e;
e++;
}
str_t[i] = '\0';
token.var.i = atoi(str_t);
}
// operator
else
{
token.type = token_operator;
switch(*e)
{
case '(':
token.ator = operators[oper_lparen];
break;
case ')':
token.ator = operators[oper_rparen];
break;
case '+':
token.ator = operators[oper_plus];
break;
case '-':
token.ator = operators[oper_minus];
break;
case '*':
token.ator = operators[oper_multiply];
break;
case '/':
token.ator = operators[oper_divide];
break;
case '%':
token.ator = operators[oper_mod];
break;
case '<':
if(*(e + 1) == '=')
{
token.ator = operators[oper_le];
e++;
break;
}
else
{
token.ator = operators[oper_lt];
break;
}
case '>':
if(*(e + 1) == '=')
{
token.ator = operators[oper_ge];
e++;
break;
}
else
{
token.ator = operators[oper_gt];
break;
}
case '=':
if(e[1] == '=')
{
token.ator = operators[oper_eq];
e++;
break;
}
else
{
printf(1, "expression error\n");
exit();
}
case '!':
if(*(e + 1) == '=')
{
token.ator = operators[oper_ne];
e++;
break;
}
else
{
token.ator = operators[oper_not];
break;
}
case '&':
token.ator = operators[oper_and];
break;
case '|':
token.ator = operators[oper_or];
break;
default:
printf(1, "expression error\n");
}
e++;
}
return token;
}
VARIANT
eval(char *eval)
{
PTLIST s_num;
PTLIST s_ator;
TOKEN token;
TOKEN t;
TOKEN a, b, c;
a.type = token_null;
b.type = token_null;
c.type = token_null;
e = eval;
s_num = stack_ini();
s_ator = stack_ini();
token.type = token_operator;
token.ator = operators[oper_min];
stack_push(s_ator, token);
while(*e)
{
token = next_token();
if(token.type == token_operand)
{
stack_push(s_num, token);
continue;
}
else if(token.type == token_operator)
{
t = stack_top(s_ator);
while(token.ator.icp <= t.ator.isp || token.ator.oper == oper_rparen)
{
t = stack_pop(s_ator);
switch(t.ator.oper)
{
case oper_plus :
a = stack_pop(s_num);
b = stack_pop(s_num);
if(a.var.type == var_string && b.var.type == var_string)
{
c.type = token_operand;
c.var.type = var_string;
_strcat(b.var.s, a.var.s);
strcpy(c.var.s, b.var.s);
stack_push(s_num, c);
}
else if(a.var.type == var_int && b.var.type == var_int)
{
c.var.i = b.var.i + a.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
}
else
{
printf(1, "expression error\n");
}
break;
case oper_minus :
a = stack_pop(s_num);
b = stack_pop(s_num);
c.var.i = b.var.i - a.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
break;
case oper_multiply :
a = stack_pop(s_num);
b = stack_pop(s_num);
c.var.i = b.var.i * a.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
break;
case oper_divide :
a = stack_pop(s_num);
b = stack_pop(s_num);
c.var.i = b.var.i / a.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
break;
case oper_lt :
a = stack_pop(s_num);
b = stack_pop(s_num);
c.var.i = b.var.i < a.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
break;
case oper_gt :
a = stack_pop(s_num);
b = stack_pop(s_num);
c.var.i = b.var.i > a.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
break;
case oper_eq :
a = stack_pop(s_num);
b = stack_pop(s_num);
c.var.i = b.var.i == a.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
break;
case oper_le :
a = stack_pop(s_num);
b = stack_pop(s_num);
c.var.i = b.var.i <= a.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
break;
case oper_ge :
a = stack_pop(s_num);
b = stack_pop(s_num);
c.var.i = b.var.i >= a.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
break;
case oper_ne :
a = stack_pop(s_num);
b = stack_pop(s_num);
c.var.i = b.var.i != a.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
break;
case oper_and :
a = stack_pop(s_num);
b = stack_pop(s_num);
c.var.i = b.var.i && a.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
break;
case oper_or :
a = stack_pop(s_num);
b = stack_pop(s_num);
c.var.i = b.var.i || a.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
break;
case oper_not :
b = stack_pop(s_num);
c.var.i = !b.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
break;
case oper_lparen :
if(*e == '\0')
{
goto con;
}
token = next_token();
break;
default:
break;
}
t = stack_top(s_ator);
}
stack_push(s_ator, token);
con:
continue;
}
else
{
printf(1, "expression error\n");
}
}
t = stack_top(s_ator);
while(t.ator.oper != oper_min)
{
t = stack_pop(s_ator);
switch(t.ator.oper)
{
case oper_plus :
a = stack_pop(s_num);
b = stack_pop(s_num);
if(a.var.type == var_string && b.var.type == var_string)
{
c.type = token_operand;
c.var.type = var_string;
_strcat(b.var.s, a.var.s);
strcpy(c.var.s, b.var.s);
stack_push(s_num, c);
}
else if(a.var.type == var_int && b.var.type == var_int)
{
c.var.i = b.var.i + a.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
}
else
{
printf(1, "expression error\n");
}
break;
case oper_minus :
a = stack_pop(s_num);
b = stack_pop(s_num);
c.var.i = b.var.i - a.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
break;
case oper_multiply :
a = stack_pop(s_num);
b = stack_pop(s_num);
c.var.i = b.var.i * a.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
break;
case oper_divide :
a = stack_pop(s_num);
b = stack_pop(s_num);
c.var.i = b.var.i / a.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
break;
case oper_lt :
a = stack_pop(s_num);
b = stack_pop(s_num);
c.var.i = b.var.i < a.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
break;
case oper_gt :
a = stack_pop(s_num);
b = stack_pop(s_num);
c.var.i = b.var.i > a.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
break;
case oper_eq :
a = stack_pop(s_num);
b = stack_pop(s_num);
c.var.i = b.var.i == a.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
break;
case oper_le :
a = stack_pop(s_num);
b = stack_pop(s_num);
c.var.i = b.var.i <= a.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
break;
case oper_ge :
a = stack_pop(s_num);
b = stack_pop(s_num);
c.var.i = b.var.i >= a.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
break;
case oper_ne :
a = stack_pop(s_num);
b = stack_pop(s_num);
c.var.i = b.var.i != a.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
break;
case oper_and :
a = stack_pop(s_num);
b = stack_pop(s_num);
c.var.i = b.var.i && a.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
break;
case oper_or :
a = stack_pop(s_num);
b = stack_pop(s_num);
c.var.i = b.var.i || a.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
break;
case oper_not :
b = stack_pop(s_num);
c.var.i = !b.var.i;
c.type = token_operand;
c.var.type = var_int;
stack_push(s_num, c);
break;
default:
break;
}
t = stack_top(s_ator);
}
c = stack_pop(s_num);
if(s_num->next == 0)
{
stack_free(s_num);
stack_free(s_ator);
return c.var;
}
else
{
printf(1, "expression error\n");
stack_free(s_num);
stack_free(s_ator);
exit();
}
}
// grammar
keywords
yacc(STRING line)
{
if(!stricmp(line, "INPUT ", 6))
{
return key_input;
}
else if(!stricmp(line, "PRINT ", 6))
{
return key_print;
}
else if(!stricmp(line, "FOR ", 4))
{
return key_for;
}
else if(!stricmp(line, "ENDFOR", 6))
{
return key_endfor;
}
else if(!stricmp(line, "IF ", 3))
{
return key_if;
}
else if(!stricmp(line, "ELSE", 4))
{
return key_else;
}
else if(!stricmp(line, "ENDIF", 5))
{
return key_endif;
}
else if(!stricmp(line, "LET ", 4))
{
return key_let;
}
else if(!stricmp(line, "LIST", 4))
{
return key_list;
}
else if(!stricmp(line, "GOTO ", 5))
{
return key_goto;
}
else if(!stricmp(line, "WHILE ", 6))
{
return key_while;
}
else if(!stricmp(line, "WEND", 4))
{
return key_wend;
}
else if(*line == '\0')
{
return key_null;
}
else
{
printf(1, "grammar error:yacc\n");
exit();
}
}
void
exec_input(STRING line)
{
const char *cs = line;
int n;
STRING buf;
cs += 5;
while(*cs && isspace(*cs))
{
cs++;
}
if(isalpha(*cs) && *(cs + 1) == '\0')
{
n = toupper(*cs) - 'A';
}
else
{
printf(1, "grammar error:input\n");
exit();
}
gets(buf, 128);
if(isalpha(buf[0]))
{
memory[n].type = var_string;
strcpy(memory[n].s,buf);
}
else
{
memory[n].type = var_int;
memory[n].i = atoi(buf);
}
}
void
exec_print(STRING line)
{
char *s = line;
VARIANT v;
char bufc;
char bufs[2];
s += 6;
if(*s == '"')
{
s++;
while(*s != '"')
{
if(s[0] == '\\' && s[1] == 'n')
{
printf(1, "\n");
s += 2;
}
else if(s[0] == '\\' && s[1] == 't')
{
printf(1, "\t");
s += 2;
}
else
{
bufc = *s;
bufs[0] = bufc;
bufs[1] = '\0';
printf(1, "%s", bufs);
s++;
}
}
}
else
{
v = eval(s);
if(v.type == var_string)
{
printf(1, "%s", v.s);
}
else if(v.type == var_int)
{
printf(1, "%d", v.i);
}
}
}
void
exec_for(STRING line)
{
STRING sl;
int top;
char *et = 0;
char *s;
strcpy(sl, line);
s = sl;
top = top_for + 1;
s += 4;
if(top >= MEMORY_SIZE)
{
printf(1, "error:for\n");
exit();
}
while(*s && isspace(*s)) s++;
if(isalpha(*s) && !isalnum(s[1]))
{
stack_for[top].id = toupper(*s) - 'A';
stack_for[top].ln = cp;
s++;
}
else
{
printf(1, "grammar error:for\n");
exit();
}
while(*s && isspace(*s)) s++;
if(*s == '=')
{
s++;
}
else
{
printf(1, "grammar error:for\n");
exit();
}
while(*s && isspace(*s)) s++;
et = _strstr(s, " TO ");
if(et != 0)
{
*et = '\0';
memory[stack_for[top].id] = eval(s);
s = et + 4;
}
else
{
printf(1, "grammar error:for\n");
exit();
}
et = _strstr(s, " STEP ");
if(et != 0)
{
*et = '\0';
stack_for[top].target = eval(s).i;
s = et + 5;
stack_for[top].step = eval(s).i;
if(stack_for[top].step < 1E-6 && (0-stack_for[top].step) < 1E-6)
{
printf(1, "step is too small\n");
exit();
}
}
else
{
stack_for[top].target = eval(s).i;
stack_for[top].step = 1;
}
if( (stack_for[top].step >= 0 &&
memory[stack_for[top].id].i > stack_for[top].target) ||
(stack_for[top].step <= 0 &&
memory[stack_for[top].id].i < stack_for[top].target) )
{
while(yacc(code[cp].line) != key_endfor)
{
cp++;
}
return;
}
else
{
top_for++;
}
}
void
exec_endfor(STRING line)
{
if(strcmp(line, "ENDFOR"))
{
printf(1, "grammar error:endfor\n");
exit();