path: root/42sh/src/parser/parser_commands.c

#include <err.h>

#include "parser_functions.h"
#include "parser_utils.h"

static struct ast *cons_redirs(struct lexer *lexer, enum parser_state *state,
                               struct ast *root)
{
    struct token next = lexer_peek(lexer);

    while (TST_REDIR)
    {
        // The redir constructions are not consistents between the two
        // grammars that can create redirs
        // This is normal as theses redirs don't serve the same purposes
        // This redir here is meant to redir a chuncky command
        // While the one on the prefix grammar is meant for redirs mixed
        // with assignments of variables
        struct ast *redir = parse_redirection(lexer, state);
        next = lexer_peek(lexer);
        if (error_check(root, state, next))
        {
            return NULL;
        }
        set_left(redir, root);
        root = redir;
    }

    return root;
}

struct ast *parse_command(struct lexer *lexer, enum parser_state *state)
{
    struct token next = lexer_peek(lexer);

    if (error_check(NULL, state, next))
    {
        return NULL;
    }

    // Case where we are in a loop
    if (next.type == TOKEN_IF || next.type == TOKEN_WHILE
        || next.type == TOKEN_UNTIL || next.type == TOKEN_FOR
        || next.type == TOKEN_CURLY_LEFT || next.type == TOKEN_PAR_LEFT)
    {
        struct ast *loops = parse_shell_command(lexer, state);
        next = lexer_peek(lexer);

        if (error_check(loops, state, next))
        {
            return NULL;
        }

        return cons_redirs(lexer, state, loops);
    }
    // Case where we're sure we have a prefix
    else if (next.type == TOKEN_ASS_WORD || TST_REDIR)
    {
        return parse_simple_command(lexer, state);
    }
    // Ambiguous case where a WORD can be used in simple_command or in fundec
    // We know that parse_simple will crash if something after the WORD is
    // a parenthesis. So we just save the word in case and call simple command
    else
    {
        next = lexer_peek(lexer);
        if (next.type != TOKEN_WORD)
        {
            QUICK_CLEANUP
        }

        struct string *cpy =
            string_create((next.value) ? next.value->data : NULL);
        if (cpy == NULL)
        {
            QUICK_CLEANUP
        }
        struct ast *temp = parse_simple_command(lexer, state);

        next = lexer_peek(lexer);

        // I have the feeling that this can be problematic in the case where
        // we have a function definiton and a subshell
        if (next.type == TOKEN_PAR_LEFT)
        {
            ast_free(temp);
            temp = NULL;
        }

        if (temp != NULL)
        {
            string_free(cpy);
            return temp;
        }
        else
        {
            // Just like it never happened...
            *state = OK;

            if (next.type == TOKEN_WORD)
            {
                string_free(cpy);
                temp = parse_funcdec(lexer, state, NULL);
            }
            else
            {
                temp = parse_funcdec(lexer, state, cpy);
            }

            next = lexer_peek(lexer);
            if (error_check(temp, state, next))
            {
                return NULL;
            }

            return cons_redirs(lexer, state, temp);
        }
    }
}

struct ast *parse_shell_command(struct lexer *lexer, enum parser_state *state)
{
    struct token next = lexer_peek(lexer);
    switch (next.type)
    {
    case TOKEN_IF:
        return parse_rule_if(lexer, state);
    case TOKEN_WHILE:
        return parse_rule_while(lexer, state);
    case TOKEN_UNTIL:
        return parse_rule_until(lexer, state);
    case TOKEN_FOR:
        return parse_rule_for(lexer, state);
    case TOKEN_CURLY_LEFT:
        lexer_pop(lexer);
        struct ast *lst = parse_compound_list(lexer, state);
        next = lexer_peek(lexer);

        if (error_check(lst, state, next))
        {
            return NULL;
        }

        if (next.type != TOKEN_CURLY_RIGHT)
        {
            cleanup(lst, state);
            return NULL;
        }

        lexer_pop(lexer);
        return lst;
    case TOKEN_PAR_LEFT:
        lexer_pop(lexer);
        struct ast *subshell = ast_create(AST_SUBSHELL);

        if (subshell == NULL)
        {
            QUICK_CLEANUP
        }

        struct ast *body = parse_compound_list(lexer, state);
        next = lexer_peek(lexer);
        set_left(subshell, body);

        if (error_check(subshell, state, next))
        {
            return NULL;
        }

        if (next.type != TOKEN_PAR_RIGHT)
        {
            cleanup(subshell, state);
            return NULL;
        }

        lexer_pop(lexer);
        return subshell;
    default:
        // This case should not happen but just in case + for pedantic warnings
        cleanup(NULL, state);
        return NULL;
    }
}

struct ast *parse_simple_command(struct lexer *lexer, enum parser_state *state)
{
    struct token next = lexer_peek(lexer);
    struct ast *root = NULL;
    struct ast *up = NULL;

    // Should be enough to guard against the case where we have no prefix/WORDs
    if (next.type != TOKEN_ASS_WORD && next.type != TOKEN_IONUMBER
        && next.type != TOKEN_REDIR && next.type != TOKEN_WORD)
    {
        // Honnestly, it's quite useful and also puts me below 40 lines
        QUICK_CLEANUP
    }
    struct ast *lst = ast_create(AST_LIST);

    if (lst == NULL)
    {
        QUICK_CLEANUP
    }

    size_t i = 0;

    while (next.type == TOKEN_ASS_WORD || TST_REDIR)
    {
        if (next.type == TOKEN_ASS_WORD)
        {
            struct ast *var = parse_prefix(lexer, state);
            next = lexer_peek(lexer);
            if (error_check(var, state, next))
            {
                return NULL;
            }

            set_i(lst, var, i);
            i++;
        }
        else
        {
            struct ast *redir = parse_prefix(lexer, state);
            next = lexer_peek(lexer);
            if (error_check(redir, state, next))
            {
                return NULL;
            }

            if (root == NULL || up == NULL)
            {
                root = redir;
                up = redir;
                set_left(up, lst);
            }
            else
            {
                set_left(up, redir);
                set_left(redir, lst);
                up = redir;
            }
        }

        next = lexer_peek(lexer);
    }

    struct ast *son = parse_element(lexer, state, lst, up);
    if (root == NULL)
    {
        root = son;
    }
    next = lexer_peek(lexer);

    if (error_check(root, state, next))
    {
        // You never know if it was only variable assignment
        // If so, this would never be attached to root
        // cleanup(lst, state); // this one may not be necessary ~
        return NULL;
    }

    return (root == NULL) ? lst : root;
}

// This function takes care of the reallocation and all the checks that
// comes with calling realloc. (Mainly freeing stuff and exiting)
static struct string **_realloc_ast_command(struct ast *ast, size_t *capacity)
{
    struct ast_command *ast_c = ((struct ast_command *)ast);
    size_t i = 0;
    while (i < *capacity && ast_c->args[i])
    {
        i++;
    }
    struct string **p =
        realloc(ast_c->args, (i + CMDSIZE) * sizeof(struct string *));
    if (!p)
    {
        errx(EXIT_FAILURE, "Realloc failed.");
    }
    ast_c->args = p;
    *capacity = i + CMDSIZE;
    memset(ast_c->args + i, 0, (CMDSIZE) * sizeof(struct string *));
    return p;
}

// Does not EXACTLY follows the grammar but it's close enough
// Here is the pattern it produces:
// element = { (WORD | redirection) };
// Plus, it directly changes the tree instead of returning an ast to be
// attached to the parent node
struct ast *parse_element(struct lexer *lexer, enum parser_state *state,
                          struct ast *lst, struct ast *up)
{
    struct ast *root = up;
    struct token next = lexer_peek(lexer);
    struct ast *base = ast_create(AST_COMMAND);
    int child_filled = 0;
    if (base == NULL)
    {
        QUICK_CLEANUP;
    }

    struct string **space = calloc(11, sizeof(struct string *));
    if (space == NULL)
    {
        cleanup(base, state);
        return NULL;
    }

    size_t capacity = CMDSIZE;
    size_t i = 0;

    ((struct ast_command *)base)->args = space;

    while (ISWORD(next.type) || TST_REDIR)
    {
        if (!(ISWORD(next.type)))
        {
            struct ast *redir = parse_redirection(lexer, state);
            // Because state is at ERROR state, I'm sure the 2 will be executed
            if (error_check(root, state, next) && error_check(lst, state, next))
            {
                return NULL;
            }
            if (root == NULL)
            {
                root = redir;
                up = redir;
            }
            set_left(up, redir);
            set_left(redir, lst);
            up = redir;
        }
        else
        {
            if (!child_filled)
            {
                child_filled = 1;
            }
            if (i == capacity)
            {
                space = _realloc_ast_command(base, &capacity);
            }

            litteral_reserved_word(&next);
            space[i] = next.value;
            i++;
            lexer_pop(lexer);
        }
        next = lexer_peek(lexer);
    }

    // In case we created the child for nothing and he wasn't filled
    if (!child_filled)
    {
        ast_free(base);
    }
    else
    {
        size_t lst_end = list_length(lst);
        set_i(lst, base, lst_end);
    }

    // No need to reassign the space variable to the ast here because the worst
    // that can happens is if it has been moved becasue of realloc() and this
    // case has been dealt with

    return (root == NULL) ? lst : root;
}

struct ast *parse_prefix(struct lexer *lexer, enum parser_state *state)
{
    struct token next = lexer_peek(lexer);
    if (next.type == TOKEN_ASS_WORD)
    {
        struct ast *assign = assign_setup(next);
        lexer_pop(lexer);
        if (assign == NULL)
        {
            QUICK_CLEANUP
        }
        return assign;
    }
    else if (TST_REDIR)
    {
        return parse_redirection(lexer, state);
    }
    else
    {
        QUICK_CLEANUP
    }
}