Value* Value_copy(const Value* val) {
Value* ret;
switch(val->type) {
case VAL_INT:
ret = ValInt(val->ival);
break;
case VAL_REAL:
ret = ValReal(val->rval);
break;
case VAL_FRAC:
ret = ValFrac(Fraction_copy(val->frac));
break;
case VAL_EXPR:
ret = ValExpr(BinOp_copy(val->expr));
break;
case VAL_CALL:
ret = ValCall(FuncCall_copy(val->call));
break;
case VAL_UNARY:
ret = ValUnary(UnOp_copy(val->term));
break;
case VAL_VAR:
ret = ValVar(val->name);
break;
case VAL_VEC:
ret = ValVec(Vector_copy(val->vec));
break;
case VAL_NEG:
/* Shouldn't be reached, but so easy to code */
ret = ValNeg();
break;
case VAL_ERR:
ret = ValErr(Error_copy(val->err));
break;
default:
typeError("Unknown value type: %d.", val->type);
ret = NULL;
break;
}
return ret;
}
static void treeAddValue(BinOp** tree, BinOp** prev, BINTYPE op, Value* val) {
BinOp* parent = *tree;
BinOp* cur = *tree;
BinOp* next;
/*
Descend down the right side of the tree until we find either an empty node or
an operator with a higher precedence than the current one.
*/
while(cur->b && BinOp_cmp(cur->type, op) < 0) {
parent = cur;
cur = cur->b->expr;
}
if(BinOp_cmp(cur->type, op) >= 0) {
/* Replace current node with new one */
if(cur == *tree) {
/* At the tree's root */
next = BinOp_new(op, ValExpr(*tree), NULL);
*tree = next;
}
else {
/* Somewhere in the tree */
next = BinOp_new(op, parent->b, NULL);
parent->b = ValExpr(next);
}
(*prev)->b = val;
}
else {
/* New node is child of current node */
next = BinOp_new(op, val, NULL);
(*prev)->b = ValExpr(next);
}
*prev = next;
}
Value* Value_parse(const char** expr, char sep, char end, parser_cb* cb) {
Value* val;
BINTYPE op = BIN_UNK;
BinOp* tree = NULL;
BinOp* prev;
while(1) {
/* Get next value */
val = Value_next(expr, end, cb);
/* Error parsing next value? */
if(val->type == VAL_ERR) {
if(tree) {
BinOp_free(tree);
}
return val;
}
/* End of input? */
if(val->type == VAL_END) {
if(tree) {
BinOp_free(tree);
}
return val;
}
/* Special case: negative value */
if(val->type == VAL_NEG) {
Value_free(val);
BinOp* cur = BinOp_new(BIN_MUL, ValInt(-1), NULL);
if(tree) {
prev->b = ValExpr(cur);
}
else {
tree = cur;
}
prev = cur;
continue;
}
/* Get next operator if it exists */
op = BinOp_nextType(expr, sep, end);
/* Invalid operator? Return syntax error */
if(op == BIN_UNK) {
/* Exit gracefully and return error */
if(tree) {
BinOp_free(tree);
}
Value_free(val);
return ValErr(badChar(**expr));
}
/* End of the statement? */
else if(op == BIN_END) {
/* Only skip end character if there's only one value to parse */
if(!sep && **expr && **expr == end) {
(*expr)++;
}
/* If there was only one value, return it */
if(!tree) {
return val;
}
/* Otherwise, place the final value into the tree and break out of the parse loop */
prev->b = val;
break;
}
/* Tree not yet begun? Initialize it! */
if(tree == NULL) {
tree = BinOp_new(op, val, NULL);
prev = tree;
}
else {
/* Tree already started, so add to it */
treeAddValue(&tree, &prev, op, val);
}
}
return ValExpr(tree);
}
Expression* Expression_parse(const char** expr) {
Expression* ret = NULL;
Variable* var;
Value* val;
const char* equals = strchr(*expr, '=');
if(equals == NULL) {
/* No assignment, just a plain expression. */
return parseExpr(expr);
}
/* There is an assignment */
/* First, parse the right side of the assignment */
equals++;
val = Value_parse(&equals, 0, 0);
if(val->type == VAL_ERR) {
/* A parse error occurred */
var = VarErr(Error_copy(val->err));
Value_free(val);
return Expression_new(var);
}
if(val->type == VAL_END) {
/* Empty input */
Value_free(val);
var = VarErr(earlyEnd());
return Expression_new(var);
}
/* Now parse the left side */
char* name = nextToken(expr);
if(name == NULL) {
Value_free(val);
var = VarErr(syntaxError("No variable to assign to."));
return Expression_new(var);
}
trimSpaces(expr);
if(**expr == '(') {
/* Defining a function */
(*expr)++;
/* Array of argument names */
unsigned size = 2;
char** args = fmalloc(size * sizeof(*args));
unsigned len = 0;
/* Add each argument name to the array */
char* arg = nextToken(expr);
if(arg == NULL && **expr != ')') {
/* Invalid character */
Value_free(val);
free(args);
free(name);
var = VarErr(badChar(**expr));
return Expression_new(var);
}
trimSpaces(expr);
if(arg == NULL) {
/* Empty parameter list means function with no args */
free(args);
args = NULL;
len = 0;
}
else {
/* Loop through each argument in the list */
while(**expr == ',' || **expr == ')') {
args[len++] = arg;
if(**expr == ')')
break;
(*expr)++;
/* Expand argument array if it's too small */
if(len >= size) {
size *= 2;
args = frealloc(args, size * sizeof(*args));
}
arg = nextToken(expr);
if(arg == NULL) {
/* Invalid character */
Value_free(val);
free(name);
/* Free argument names and return */
unsigned i;
for(i = 0; i < len; i++) {
free(args[i]);
}
free(args);
var = VarErr(badChar(**expr));
return Expression_new(var);
}
trimSpaces(expr);
}
}
if(**expr != ')') {
/* Invalid character inside argument name list */
Value_free(val);
free(name);
/* Free argument names and return */
unsigned i;
for(i = 0; i < len; i++) {
free(args[i]);
}
free(args);
var = VarErr(badChar(**expr));
return Expression_new(var);
}
/* Skip closing parenthesis */
(*expr)++;
trimSpaces(expr);
if(**expr != '=') {
Value_free(val);
free(name);
unsigned i;
for(i = 0; i < len; i++) {
free(args[i]);
}
free(args);
var = VarErr(badChar(**expr));
return Expression_new(var);
}
/* Construct function and return it */
Function* func = Function_new(len, args, val);
var = VarFunc(name, func);
free(name);
ret = Expression_new(var);
}
else {
/* Defining a variable */
if(**expr != '=') {
/* In-place manipulation */
BINTYPE bin = BinOp_nextType(expr, 0, 0);
/* Still not an equals sign means invalid character */
if(**expr != '=') {
Value_free(val);
free(name);
var = VarErr(badChar(**expr));
return Expression_new(var);
}
val = ValExpr(BinOp_new(bin, ValVar(name), val));
}
var = VarValue(name, val);
free(name);
ret = Expression_new(var);
}
return ret;
}
