j-lang/src/frontend/parser.h

#ifndef JLANG_PARSER_H
#define JLANG_PARSER_H
/*
    Convierte tokens en un arbol
*/

#include "lexer.h"

typedef enum {
  NODE_INT_LIT,    // literal entero
  NODE_STRING_LIT, // literal string
  NODE_VAR,        // referencia a variable
  NODE_ASSIGN,     // asignacion: x = expr
  NODE_BINOP,      // operacion binaria: a + b
  NODE_PRINT,      // print(expr)
  NODE_IF,         // if cond: bloque
  NODE_WHILE,      // while cond: bloque
  NODE_BLOCK,      // secuencia de statements
} NodeType;

typedef struct ASTNode {
  NodeType type;
  union {
    int int_val;      // NODE_INT_LIT
    char *string_val; // NODE_STRING_LIT
    struct {
      char *name;
      struct ASTNode *value;
    } assign; // NODE_ASSIGN
    struct {
      char op;
      struct ASTNode *left;
      struct ASTNode *right;
    } binop; // NODE_BINOP
    struct {
      struct ASTNode *expr;
    } print; // NODE_PRINT
    struct {
      struct ASTNode **stmts;
      int count;
    } block; // NODE_BLOCK
    struct {
      struct ASTNode *cond;
      struct ASTNode *body;
    } while_loop; // NODE_WHILE
  } data;
} ASTNode;

ASTNode *make_node(NodeType type) {
  ASTNode *node = (ASTNode *)malloc(sizeof(ASTNode));
  node->type = type;
  return node;
}

int pos = 0;

ASTNode *parse_term(Token *tokens) {
  if (tokens[pos].type == TOK_INT) {
    ASTNode *node = make_node(NODE_INT_LIT);
    node->data.int_val = atoi(tokens[pos].value);
    pos++;
    return node;
  } else if (tokens[pos].type == TOK_ID) {
    ASTNode *node = make_node(NODE_VAR);
    node->data.string_val = tokens[pos].value;
    pos++;
    return node;
  }
  printf("ERROR: esperaba INT o ID, encontré tipo %d\n", tokens[pos].type);
  exit(1);
}

ASTNode *parse_expr(Token *tokens) {
  ASTNode *left = parse_term(tokens);

  while (tokens[pos].type == TOK_PLUS || tokens[pos].type == TOK_MINUS ||
         tokens[pos].type == TOK_STAR || tokens[pos].type == TOK_SLASH ||
         tokens[pos].type == TOK_LT || tokens[pos].type == TOK_GT) {
    char op = tokens[pos].value[0]; // +,-,*,/
    pos++;
    ASTNode *right = parse_term(tokens);

    ASTNode *binop = make_node(NODE_BINOP);
    binop->data.binop.op = op;
    binop->data.binop.left = left;
    binop->data.binop.right = right;
    left = binop; // encadenar: (a + b) + c
  }
  return left;
}

ASTNode *parse_statement(Token *tokens) {
  if (tokens[pos].type == TOK_ID) {
    char *name = tokens[pos].value;
    pos++; // consumir ID
    pos++; // consumir "="
    ASTNode *value = parse_expr(tokens);

    ASTNode *node = make_node(NODE_ASSIGN);
    node->data.assign.name = name;
    node->data.assign.value = value;
    return node;
  }
  if (tokens[pos].type == TOK_PRINT) {
    pos++; // consumir "print"
    ASTNode *expr = parse_expr(tokens);

    ASTNode *node = make_node(NODE_PRINT);
    node->data.print.expr = expr;
    return node;
  }

  if (tokens[pos].type == TOK_WHILE) {
    pos++; // consumir while
    ASTNode *cond = parse_expr(tokens);
    pos++; // consumir ":"
    pos++; // consumir NEWLINE
    pos++; // consumir INDENT

    // Parsear bloque de statements hasta DEDENT
    ASTNode *body = make_node(NODE_BLOCK);
    body->data.block.stmts = (ASTNode **)malloc(sizeof(ASTNode *) * 256);
    body->data.block.count = 0;
    while (tokens[pos].type != TOK_DEDENT) {
      body->data.block.stmts[body->data.block.count++] =
          parse_statement(tokens);
      if (tokens[pos].type == TOK_NEWLINE) {
        pos++;
      }
    }
    pos++; // Consumir DEDENT

    ASTNode *node = make_node(NODE_WHILE);
    node->data.while_loop.cond = cond;
    node->data.while_loop.body = body;
    return node;
  }
  printf("ERROR: statement inesperado\n");
  exit(1);
}

ASTNode *parse(Token *tokens, int token_count) {
  ASTNode *block = make_node(NODE_BLOCK);
  block->data.block.stmts = (ASTNode **)malloc(sizeof(ASTNode *) * 256);
  block->data.block.count = 0;

  while (pos < token_count) {
    if (tokens[pos].type == TOK_NEWLINE) {
      pos++; // Saltar newlines sueltos
      continue;
    }
    block->data.block.stmts[block->data.block.count++] =
        parse_statement(tokens);

    // Consumir newline despues del statement
    if (pos < token_count && tokens[pos].type == TOK_NEWLINE) {
      pos++;
    }
  }
  return block;
}

void ast_print(ASTNode *node, const char *prefix, int is_last) {
  if (!node)
    return;

  printf("%s", prefix);
  printf(is_last ? "`-- " : "|-- ");

  // Construir nuevo prefijo para hijos
  char new_prefix[256];
  snprintf(new_prefix, sizeof(new_prefix), "%s%s", prefix,
           is_last ? "    " : "|   ");

  switch (node->type) {
  case NODE_WHILE:
    printf("NODE_WHILE\n");
    ast_print(node->data.while_loop.cond, new_prefix, 0);
    ast_print(node->data.while_loop.body, new_prefix, 1);
    break;

  case NODE_INT_LIT:
    printf("NODE_INT_LIT(%d)\n", node->data.int_val);
    break;

  case NODE_STRING_LIT:
    printf("NODE_STRING_LIT(\"%s\")\n", node->data.string_val);
    break;

  case NODE_VAR:
    printf("NODE_VAR(\"%s\")\n", node->data.string_val);
    break;

  case NODE_ASSIGN:
    printf("NODE_ASSIGN { name:\"%s\" }\n", node->data.assign.name);
    ast_print(node->data.assign.value, new_prefix, 1);
    break;

  case NODE_BINOP:
    printf("NODE_BINOP('%c')\n", node->data.binop.op);
    ast_print(node->data.binop.left, new_prefix, 0);
    ast_print(node->data.binop.right, new_prefix, 1);
    break;

  case NODE_PRINT:
    printf("NODE_PRINT\n");
    ast_print(node->data.print.expr, new_prefix, 1);
    break;

  case NODE_BLOCK:
    printf("NODE_BLOCK\n");
    for (int i = 0; i < node->data.block.count; i++) {
      ast_print(node->data.block.stmts[i], new_prefix,
                i == node->data.block.count - 1);
    }
    break;

  default:
    printf("UNKNOWN\n");
    break;
  }
}

void ast_debug(ASTNode *node) { ast_print(node, "", 1); }

#endif