Add a parser grammar

Currently this is a subset of the grammar, enough to get reasonable work
going.

doc/parser_grammar.txt

@@ -27,9 +27,9 @@
 
 <memory_expression> ::= <label_reference> | <register_expression>
 
-<register_expression> ::= <register> <register_index>? <register_offset>?
+<register_expression> ::= <register> ( <plus> <register> <asterisk> <number> )? ( <plus_or_minus> <number> )?
 
-<register_index> ::= <plus> <register> <asterisk> <number>
+<register_displacement> ::= <plus> <register> <asterisk> <number>
 
 <register_offset> ::= <plus_or_minus> <number>
 

src/ast.c

@@ -1,84 +0,0 @@
-#include "ast.h"
-#include "error.h"
-#include <string.h>
-
-error_t *err_node_children_cap = &(error_t){
-    .message = "Failed to increase ast node children, max capacity reached"};
-
-error_t *ast_node_alloc(ast_node_t **output) {
-    *output = nullptr;
-
-    ast_node_t *node = calloc(1, sizeof(ast_node_t));
-    if (node == nullptr)
-        return err_allocation_failed;
-
-    *output = node;
-    return nullptr;
-}
-
-void ast_node_free_value(ast_node_t *node) {
-    // TODO: decide how value ownership will work and clean it up here
-}
-
-void ast_node_free(ast_node_t *node) {
-    if (node == nullptr)
-        return;
-    if (node->children) {
-        for (size_t i = 0; i < node->len; ++i)
-            ast_node_free(node->children[i]);
-    }
-
-    ast_node_free_value(node);
-
-    memset(node, 0, sizeof(ast_node_t));
-    free(node);
-}
-
-/**
- * @pre node->children must be nullptr
- */
-error_t *ast_node_alloc_children(ast_node_t *node) {
-    node->children = calloc(node_default_children_cap, sizeof(ast_node_t *));
-    if (node->children == nullptr)
-        return err_allocation_failed;
-
-    node->cap = node_default_children_cap;
-    return nullptr;
-}
-
-error_t *ast_node_grow_cap(ast_node_t *node) {
-    if (node->cap >= node_max_children_cap) {
-        return err_node_children_cap;
-    }
-
-    size_t new_cap = node->cap * 2;
-    if (new_cap > node_max_children_cap) {
-        new_cap = node_max_children_cap;
-    }
-
-    ast_node_t **new_children =
-        realloc(node->children, new_cap * sizeof(ast_node_t *));
-    if (new_children == nullptr) {
-        return err_allocation_failed;
-    }
-
-    node->children = new_children;
-    node->cap = new_cap;
-
-    return nullptr;
-}
-
-error_t *ast_node_add_child(ast_node_t *node, ast_node_t *child) {
-    error_t *err = nullptr;
-    if (node->children == nullptr)
-        err = ast_node_alloc_children(node);
-    else if (node->len >= node->cap)
-        err = ast_node_grow_cap(node);
-    if (err)
-        return err;
-
-    node->children[node->len] = child;
-    node->len += 1;
-
-    return nullptr;
-}

src/ast.h

@@ -1,72 +0,0 @@
-#ifndef INCLUDE_SRC_AST_H_
-#define INCLUDE_SRC_AST_H_
-
-#include "error.h"
-#include "lexer.h"
-#include <stddef.h>
-#include <stdint.h>
-
-typedef enum node_id {
-    NODE_PROGRAM,
-    NODE_DIRECTIVE,
-    NODE_LABEL,
-    NODE_INSTRUCTION
-} node_id_t;
-
-typedef struct ast_node ast_node_t;
-
-constexpr size_t node_default_children_cap = 8;
-/* 65K ought to be enough for anybody */
-constexpr size_t node_max_children_cap = 1 << 16;
-
-struct ast_node {
-    node_id_t id;
-    lexer_token_t *token;
-    size_t len;
-    size_t cap;
-    ast_node_t **children;
-
-    union {
-        struct {
-            uint64_t value;
-            int size;
-        } integer;
-        char *name;
-    } value;
-};
-
-/**
- * @brief Allocates a new AST node
- *
- * Creates and initializes a new AST node with default (zero) values.
- *
- * @param[out] output Pointer to store the allocated node
- * @return error_t* nullptr on success, allocation error on failure
- */
-error_t *ast_node_alloc(ast_node_t **node);
-
-/**
- * @brief Frees an AST node and all its children recursively
- *
- * Recursively frees all children of the node, then frees the node itself.
- * If node is nullptr, the function returns without doing anything.
- *
- * @param node The node to free
- */
-void ast_node_free(ast_node_t *node);
-
-/**
- * @brief Adds a child node to a parent node
- *
- * Adds the specified child node to the parent's children array.
- * If this is the first child, the function allocates the children array.
- * If the children array is full, the function increases its capacity.
- *
- * @param node The parent node to add the child to
- * @param child The child node to add
- * @return error_t* nullptr on success, allocation error on failure,
- *                  or err_node_children_cap if maximum capacity is reached
- */
-error_t *ast_node_add_child(ast_node_t *node, ast_node_t *child);
-
-#endif // INCLUDE_SRC_AST_H_

src/error.c

@@ -10,9 +10,6 @@ error_t *const err_errorf_length = &(error_t){
     .message =
         "Formatting of another error failed to determine the error length"};
 
-error_t *err_allocation_failed =
-    &(error_t){.message = "Memory allocation failed"};
-
 error_t *errorf(const char *fmt, ...) {
     error_t *err = calloc(1, sizeof(error_t));
     if (err == nullptr)

src/error.h

@@ -18,7 +18,4 @@ static inline void error_free(error_t *err) {
     free(err);
 }
 
-/* Some global errors */
-extern error_t *err_allocation_failed;
-
 #endif // INCLUDE_SRC_ERROR_H_

src/lexer.c

@@ -20,6 +20,9 @@ error_t *err_eof =
 
 error_t *err_unknown_read = &(error_t){.message = "Unknown read error"};
 
+error_t *err_allocation_failed =
+    &(error_t){.message = "Memory allocation failed"};
+
 typedef bool (*char_predicate_t)(char);
 
 const char *lexer_token_id_to_cstr(lexer_token_id_t id) {

src/main.c

@@ -1,6 +1,5 @@
 #include "error.h"
 #include "lexer.h"
-#include "tokenlist.h"
 
 #include <limits.h>
 #include <stdio.h>
@@ -40,33 +39,24 @@ int main(int argc, char *argv[]) {
         print_fn = print_value;
     }
 
-    lexer_t *lex = &(lexer_t){};
-    error_t *err = lexer_open(lex, filename);
-    if (err)
-        goto cleanup_error;
-
-    tokenlist_t *list;
-    err = tokenlist_alloc(&list);
-    if (err)
-        goto cleanup_lexer;
-
-    err = tokenlist_fill(list, lex);
-    if (err)
-        goto cleanup_tokens;
-
-    for (auto entry = list->head; entry; entry = entry->next) {
-        print_fn(&entry->token);
+    lexer_t lex = {0};
+    lexer_token_t token;
+    error_t *err = lexer_open(&lex, filename);
+    if (err) {
+        puts(err->message);
+        error_free(err);
+        return 1;
+    }
+
+    bool keep_going = true;
+    while (keep_going && (err = lexer_next(&lex, &token)) == nullptr) {
+        keep_going = print_fn(&token);
+        free(token.value);
+    }
+
+    if (err && err != err_eof) {
+        puts(err->message);
     }
-    tokenlist_free(list);
     error_free(err);
     return 0;
-
-cleanup_tokens:
-    tokenlist_free(list);
-cleanup_lexer:
-    lexer_close(lex);
-cleanup_error:
-    puts(err->message);
-    error_free(err);
-    return 1;
 }

src/tokenlist.c

@@ -1,83 +0,0 @@
-#include "tokenlist.h"
-#include "error.h"
-#include "lexer.h"
-#include <stdlib.h>
-
-error_t *tokenlist_alloc(tokenlist_t **output) {
-    *output = nullptr;
-
-    tokenlist_t *list = calloc(1, sizeof(tokenlist_t));
-    if (list == nullptr)
-        return err_allocation_failed;
-
-    list->head = nullptr;
-    list->tail = nullptr;
-
-    *output = list;
-    return nullptr;
-}
-
-error_t *tokenlist_entry_alloc(tokenlist_entry_t **output) {
-    *output = nullptr;
-
-    tokenlist_entry_t *entry = calloc(1, sizeof(tokenlist_entry_t));
-    if (entry == nullptr)
-        return err_allocation_failed;
-
-    entry->next = nullptr;
-    entry->prev = nullptr;
-
-    *output = entry;
-    return nullptr;
-}
-
-void tokenlist_append(tokenlist_t *list, tokenlist_entry_t *entry) {
-    if (list->head == nullptr) {
-        list->head = entry;
-        list->tail = entry;
-        entry->next = nullptr;
-        entry->prev = nullptr;
-    } else {
-        entry->prev = list->tail;
-        entry->next = nullptr;
-        list->tail->next = entry;
-        list->tail = entry;
-    }
-}
-
-void tokenlist_entry_free(tokenlist_entry_t *entry) {
-    lexer_token_cleanup(&entry->token);
-    free(entry);
-}
-
-void tokenlist_free(tokenlist_t *list) {
-    if (list == nullptr)
-        return;
-
-    tokenlist_entry_t *current = list->head;
-    while (current) {
-        tokenlist_entry_t *next = current->next;
-        tokenlist_entry_free(current);
-        current = next;
-    }
-
-    free(list);
-}
-
-error_t *tokenlist_fill(tokenlist_t *list, lexer_t *lex) {
-    error_t *err = nullptr;
-    lexer_token_t token = {};
-    while ((err = lexer_next(lex, &token)) == nullptr) {
-        tokenlist_entry_t *entry;
-        err = tokenlist_entry_alloc(&entry);
-        if (err) {
-            lexer_token_cleanup(&token);
-            return err;
-        }
-        entry->token = token;
-        tokenlist_append(list, entry);
-    }
-    if (err != err_eof)
-        return err;
-    return nullptr;
-}

src/tokenlist.h

@@ -1,30 +0,0 @@
-#ifndef INCLUDE_SRC_TOKENLIST_H_
-#define INCLUDE_SRC_TOKENLIST_H_
-#include "lexer.h"
-
-typedef struct tokenlist_entry tokenlist_entry_t;
-
-struct tokenlist_entry {
-    lexer_token_t token;
-    tokenlist_entry_t *next;
-    tokenlist_entry_t *prev;
-};
-
-typedef struct tokenlist {
-    tokenlist_entry_t *head;
-    tokenlist_entry_t *tail;
-} tokenlist_t;
-
-/**
- * @brief Allocate a new doubly linked list of lexer tokens
- */
-error_t *tokenlist_alloc(tokenlist_t **list);
-
-/**
- * Consume all tokens from the lexer and add them to the list
- */
-error_t *tokenlist_fill(tokenlist_t *list, lexer_t *lex);
-
-void tokenlist_free(tokenlist_t *list);
-
-#endif // INCLUDE_SRC_TOKENLIST_H_