42sh/src/parser/grammar_advanced.c

#define _POSIX_C_SOURCE 200809L

#include "grammar_advanced.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "grammar_basic.h"

static enum ast_redir_type redir_tok_to_ast_type(enum token_type tok_type)
{
    switch (tok_type)
    {
    case TOKEN_REDIR_LEFT:
        return AST_REDIR_TYPE_LESS;
    case TOKEN_REDIR_RIGHT:
        return AST_REDIR_TYPE_GREAT;
    case TOKEN_REDIR_DOUBLE_RIGHT:
        return AST_REDIR_TYPE_DGREAT;
    case TOKEN_REDIR_LEFT_RIGHT:
        return AST_REDIR_TYPE_LESSGREAT;
    case TOKEN_REDIR_LEFT_AMP:
        return AST_REDIR_TYPE_LESSAND;
    case TOKEN_REDIR_RIGHT_AMP:
        return AST_REDIR_TYPE_GREATAND;
    case TOKEN_REDIR_RIGHT_PIPE:
        return AST_REDIR_TYPE_CLOBBER;
    default:
        return AST_REDIR_TYPE_NULL;
    }
}

struct ast *parse_redirection(struct lexer_context *ctx)
{
    struct token *token = PEEK_TOKEN();
    int io_number = -1;
    if (token->type == TOKEN_IONUMBER)
    {
        io_number = atoi(token->data);
        POP_TOKEN();
        token = PEEK_TOKEN();
    }

    if (!is_token_redir(token))
    {
        perror("Syntax error: expected a redirection token but got something "
               "else");
        return NULL;
    }

    enum ast_redir_type redir_type = redir_tok_to_ast_type(token->type);
    POP_TOKEN();

    token = PEEK_TOKEN();
    if (token->type != TOKEN_WORD)
    {
        perror("Syntax error: expected a word after redirection");
        return NULL;
    }
    char *target = strdup(token->data);
    POP_TOKEN();

    return ast_create_redir(target, io_number, redir_type);
}

struct ast *parse_prefix(struct lexer_context *ctx)
{
    struct token *token = TOKEN_PEEK();
    if (token->type == TOKEN_ASSIGNMENT_WORD)
    {
        token = TOKEN_POP();
        return ast_create_assignment_word(token->data);
    }
    else if (is_first(*token, RULE_REDIRECTION))
        return parse_redirection(ctx);
    else 
    {
        perror("Syntax error: expected a prefix (redirection or assignment)");
        return NULL;
    }
}