1 files changed, 145 insertions, 0 deletions
diff --git a/tests/sysy_lvX/072_expr_eval.sy b/tests/sysy_lvX/072_expr_eval.sy
new file mode 100644
index 0000000..08e95a0
--- /dev/null
+++ b/tests/sysy_lvX/072_expr_eval.sy
@@ -0,0 +1,145 @@
+const int TOKEN_NUM = 0, TOKEN_OTHER = 1;
+int last_char = 32, num, other;
+int cur_token;
+
+int next_char() {
+  last_char = getch();
+  return last_char;
+}
+
+int is_space(int c) {
+  if (c == 32 || c == 10) {
+    return 1;
+  }
+  else {
+    return 0;
+  }
+}
+
+int is_num(int c) {
+  if (c >= 48 && c <= 57) {
+    return 1;
+  }
+  else {
+    return 0;
+  }
+}
+
+int next_token() {
+  while (is_space(last_char)) next_char();
+  if (is_num(last_char)) {
+    num = last_char - 48;
+    while (is_num(next_char())) {
+      num = num * 10 + last_char - 48;
+    }
+    cur_token = TOKEN_NUM;
+  }
+  else {
+    other = last_char;
+    next_char();
+    cur_token = TOKEN_OTHER;
+  }
+  return cur_token;
+}
+
+int panic() {
+  putch(112);
+  putch(97);
+  putch(110);
+  putch(105);
+  putch(99);
+  putch(33);
+  putch(10);
+  return -1;
+}
+
+int get_op_prec(int op) {
+  // +, -
+  if (op == 43 || op == 45) return 10;
+  // *, /, %
+  if (op == 42 || op == 47 || op == 37) return 20;
+  // other
+  return 0;
+}
+
+void stack_push(int s[], int v) {
+  s[0] = s[0] + 1;
+  s[s[0]] = v;
+}
+
+int stack_pop(int s[]) {
+  int last = s[s[0]];
+  s[0] = s[0] - 1;
+  return last;
+}
+
+int stack_peek(int s[]) {
+  return s[s[0]];
+}
+
+int stack_size(int s[]) {
+  return s[0];
+}
+
+int eval_op(int op, int lhs, int rhs) {
+  // +
+  if (op == 43) return lhs + rhs;
+  // -
+  if (op == 45) return lhs - rhs;
+  // *
+  if (op == 42) return lhs * rhs;
+  // /
+  if (op == 47) return lhs / rhs;
+  // %
+  if (op == 37) return lhs % rhs;
+  // other
+  return 0;
+}
+
+int eval() {
+  int oprs[256] = {}, ops[256] = {};
+  // get the first value
+  if (cur_token != TOKEN_NUM) return panic();
+  stack_push(oprs, num);
+  next_token();
+  // evaluate
+  while (cur_token == TOKEN_OTHER) {
+    // get operator
+    int op = other;
+    if (!get_op_prec(op)) break;
+    next_token();
+    // handle operator
+    while (stack_size(ops) && get_op_prec(stack_peek(ops)) >= get_op_prec(op)) {
+      // evaluate the current operation
+      int cur_op = stack_pop(ops);
+      int rhs = stack_pop(oprs), lhs = stack_pop(oprs);
+      stack_push(oprs, eval_op(cur_op, lhs, rhs));
+    }
+    stack_push(ops, op);
+    // get next expression
+    if (cur_token != TOKEN_NUM) return panic();
+    stack_push(oprs, num);
+    next_token();
+  }
+  // eat ';'
+  next_token();
+  // clear the operator stack
+  while (stack_size(ops)) {
+    int cur_op = stack_pop(ops);
+    int rhs = stack_pop(oprs), lhs = stack_pop(oprs);
+    stack_push(oprs, eval_op(cur_op, lhs, rhs));
+  }
+  return stack_peek(oprs);
+}
+
+int main() {
+  int count = getint();
+  getch();
+  next_token();
+  while (count) {
+    putint(eval());
+    putch(10);
+    count = count - 1;
+  }
+  return 0;
+}