Parcel/code/src/linker.c

#include <parcel.h>
#include <ast.h>

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

// pac_copy_empty_rules_from_ast_to_grammar: Creates a grammar corresponding to the AST,
//  not copying the variants and their items, but just the rules and their names.
void pac_copy_empty_rules_from_ast_to_grammar(pac_grammar_s *grammar, pac_ast_s *ast)
{
    for(usz_t rule_index = 0; rule_index < grammar->num_rules; ++rule_index)
    {
        pac_ast_rule_s          ast_rule        = ast->rules[rule_index];
        pac_rule_s             *rule            = &grammar->rules[rule_index];
        usz_t                   len_rule_name   = strlen(ast_rule.name);
        rule->name                  = malloc(len_rule_name + 1);
        memcpy(rule->name, ast_rule.name, len_rule_name);
        rule->name[len_rule_name]   = 0x00;
    }
}

pac_set_e pac_convert_ast_set_to_grammar_set(pac_ast_set_e set)
{
    switch(set)
    {
        case PAC_AST_SET_RUNE:      return PAC_SET_RUNE;
        case PAC_AST_SET_WORD:      return PAC_SET_WORD;
        case PAC_AST_SET_INTEGER:   return PAC_SET_INTEGER;
        case PAC_AST_SET_FLOAT:     return PAC_SET_FLOAT;
    }
    return PAC_SET_INVALID;
}

pac_rule_s * pac_find_rule(pac_grammar_s *grammar, char *name)
{
    for(usz_t index = 0; index < grammar->num_rules; ++index)
    {
        if(!strcmp(grammar->rules[index].name, name))
            return &grammar->rules[index];
    }
    printf("Couldn't find refernced rule: %s\n", name);
    return NULL;
}

void pac_copy_single_variant(pac_grammar_s *grammar, pac_variant_s *variant, pac_ast_variant_s *ast_variant)
{
    variant->num_items          = ast_variant->num_items;
    variant->items              = malloc(sizeof(pac_item_s) * variant->num_items);
    for(usz_t item_index = 0; item_index < variant->num_items; ++item_index)
    {
        pac_ast_item_s          ast_item            = ast_variant->items[item_index];
        pac_item_s             *item                = &variant->items[item_index];
        switch(ast_item.type)
        {
            case PAC_AST_ITEM_INVALID:
            {
                item->type = PAC_ITEM_INVALID;
            } break;
    
            case PAC_AST_ITEM_LITERAL:
            {
                item->type = PAC_ITEM_LITERAL;
                item->data.literal.length            = ast_item.data.literal.length;
                item->data.literal.string            = ast_item.data.literal.string;         // TODO: Copy this into a grammar-owned arena!
            } break;

            case PAC_AST_ITEM_REFERENCE:
            {
                item->type = PAC_ITEM_REFERENCE;
                item->data.reference                = pac_find_rule(grammar, ast_item.data.reference.name);
            } break;

            case PAC_AST_ITEM_SET:
            {
                item->type = PAC_ITEM_SET;
                item->data.set                      = pac_convert_ast_set_to_grammar_set(ast_item.data.set);
            } break;
        }
    }
}

void pac_copy_variants_and_link_references(pac_grammar_s *grammar, pac_ast_s *ast)
{
    grammar->num_rules          = ast->num_rules;
    for(usz_t rule_index = 0; rule_index < ast->num_rules; ++rule_index)
    {
        pac_ast_rule_s          ast_rule        = ast->rules[rule_index];
        pac_rule_s             *rule            = &grammar->rules[rule_index];
        rule->num_variants          = ast_rule.num_variants;
        rule->variants              = malloc(sizeof(pac_variant_s) * rule->num_variants);
        for(usz_t variant_index = 0; variant_index < rule->num_variants; ++variant_index)
        {
            
            pac_copy_single_variant(grammar, &rule->variants[variant_index], &ast_rule.variants[variant_index]);
        }
    }
}

pac_grammar_s pac_link_grammar(pac_ast_s ast)
{
    pac_grammar_s           grammar;
    grammar.num_rules           = ast.num_rules;
    grammar.rules               = malloc(sizeof(pac_rule_s) * ast.num_rules);

    pac_copy_empty_rules_from_ast_to_grammar(&grammar, &ast);
    pac_copy_variants_and_link_references(&grammar, &ast);
    
    return grammar;
}