calculateTool.h

extern int yylineno;

void yyerror(char* s, ...);

struct symbol {
    char* name;
    double value;
    struct ast* func;
    struct symlist* syms;
};
#define NHASH 9997
struct symbol symtab[NHASH];

struct symbol* lookup(char*);

struct symlist {
    struct symbol* sym;
    struct symlist* next;
};

struct symlist* newsymlist(struct symbol* sym, struct symlist* next);
void symlistfree(struct symlist* sl);

// build-in functions
enum bifs {
    B_sqrt = 1,
    B_exp,
    B_log,
    B_print
};

struct ast {
    int nodetype;
    struct ast* l;
    struct ast* r;
};
// Q: why they only have left child node
// build-in function 
struct fncall {
    int nodetype;
    struct ast* l;
    enum  bifs functype;
};
struct ufncall {
    int nodetype;
    struct ast* l;
    struct symbol* s;
};
struct flow {
    int nodetype;
    struct ast* cond;
    struct ast* tl;
    struct ast* el;
};
struct numval {
    int nodetype;
    double number;
};
struct symref {
    int nodetype;
    struct symbol* s;
};
struct symasgn {
    int nodetype;
    struct symbol* s;
    struct ast* v;
};

struct ast *newast(int nodetype, struct ast* l, struct ast* r);
struct ast* newcmp(int cmptype, struct ast* l, struct ast* r);
struct ast* newfunc(int functype, struct ast* l);
struct ast* newcall(struct symbol* s, struct ast* l);
struct ast* newref(struct symbol* s);
struct ast* newasgn(struct symbol* s, struct ast* v);
struct ast* newnum(double d);
struct ast* newflow(int nodetype, struct ast* cond, struct ast* tl, struct ast* tr);

void dodef(struct symbol* name, struct symlist* syms, struct ast* stmts);

// calculate the ast
double eval(struct ast*);

void treefree(struct ast*);