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#include <cstdio>
#include <cctype>
#include <sstream>
#include "parser.h"
#include "exc.h"
#include "consts.h"
#include "builtin.h"
using std::stringstream;
static char buff[TOKEN_BUFF_SIZE];
static EvalObj *parse_stack[PARSE_STACK_SIZE];
extern Cons *empty_list;
Tokenizor::Tokenizor() : stream(stdin), buff_ptr(buff) {}
void Tokenizor::set_stream(FILE *_stream) {
stream = _stream;
}
#define IS_NEWLINE(ch) \
((ch) == '\n')
#define IS_BRACKET(ch) \
((ch) == '(' || (ch) == ')')
#define IS_SPACE(ch) \
((ch) == ' ' || (ch) == '\t' || IS_NEWLINE(ch))
#define IS_DELIMITER(ch) \
(IS_BRACKET(ch) || IS_SPACE(ch))
#define IS_COMMENT(ch) \
((ch) == ';')
#define POP \
do { \
*buff_ptr = 0; \
ret = string(buff); \
buff_ptr = buff; \
} while (0)
bool Tokenizor::get_token(string &ret) {
char ch;
bool flag = false;
while (fread(&ch, 1, 1, stream))
{
if (buff_ptr != buff &&
(IS_BRACKET(*buff) ||
IS_DELIMITER(ch) ||
IS_COMMENT(ch)))
{
if (IS_COMMENT(*buff))
{
if (IS_NEWLINE(ch)) buff_ptr = buff;
else buff_ptr = buff + 1;
}
else
{
POP;
flag = true;
}
}
if (!IS_SPACE(ch)) *buff_ptr++ = ch;
if (flag) return true;
}
if (buff_ptr != buff) POP;
return false; // can't read more
}
ASTGenerator::ASTGenerator() {}
EvalObj *ASTGenerator::to_float(const string &str) {
stringstream ss(str);
double val;
ss >> val;
if (ss.fail() || !ss.eof()) return NULL;
return new FloatObj(val);
}
EvalObj *ASTGenerator::to_int(const string &str) {
stringstream ss(str);
int val;
ss >> val;
if (ss.fail() || !ss.eof()) return NULL;
return new IntObj(val);
}
EvalObj *ASTGenerator::to_obj(const string &str) {
EvalObj *res = NULL;
if ((res = ASTGenerator::to_int(str)))
return res;
if ((res = ASTGenerator::to_float(str)))
return res;
return new SymObj(str);
}
Cons *ASTGenerator::absorb(Tokenizor *tk) {
EvalObj **top_ptr = parse_stack;
for (;;)
{
if (top_ptr > parse_stack && *parse_stack)
return new Cons(*(top_ptr - 1), empty_list);
string token;
if (!tk->get_token(token)) return NULL;
if (token == "(")
*top_ptr++ = NULL; // Make the beginning of a new level
else if (token == ")")
{
Cons *lst = empty_list;
while (top_ptr >= parse_stack && *(--top_ptr))
{
Cons *_lst = new Cons(*top_ptr, lst); // Collect the list
_lst->next = lst == empty_list ? NULL : lst;
lst = _lst;
}
if (top_ptr < parse_stack)
throw NormalError(READ_ERR_UNEXPECTED_RIGHT_BRACKET);
*top_ptr++ = lst;
}
else *top_ptr++ = ASTGenerator::to_obj(token);
}
}
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