print.c

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/*
 * This file is part of the Fun programming language.
 * https://fun-lang.xyz/
 *
 * Copyright 2025 Johannes Findeisen <you@hanez.org>
 * Licensed under the terms of the Apache-2.0 license.
 * https://opensource.org/license/apache-2-0
 */
 
/**
 * @file print.c
 * @brief Implements the OP_PRINT opcode for printing values in the VM.
 *
 * This file handles the OP_PRINT instruction, which prints the top value on the stack
 * to the output buffer. The value is popped from the stack.
 *
 * Behavior:
 * - Pops the value from the stack.
 * - Prints the value to the output buffer.
 *
 * Example:
 * - Bytecode: OP_PRINT
 * - Stack before: [42]
 * - Stack after: []
 */
 
case OP_PRINT: {
  Value v = pop_value(vm);
  Value snap = deep_copy_value(&v);
  free_value(v);
  if (vm->output_count < OUTPUT_SIZE) {
    int idx = vm->output_count;
    vm->output[idx] = snap;
    vm->output_is_partial[idx] = 0; // PRINT terminates the line
    vm->output_count++;
  } else {
    free_value(snap);
    fprintf(stderr, "Runtime error: output buffer overflow\n");
    exit(1);
  }
  break;
}