Hello world works
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3ecceb8902
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B715679E3A361BE6
2
Makefile
2
Makefile
@ -1,4 +1,4 @@
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CFLAGS = -std=gnu99 -Wall
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CFLAGS = -std=gnu99 -Wall -Wextra -ggdb
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all: ell
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ell: ell.c
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$(CC) $(CFLAGS) $< -o $@
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254
ell.c
254
ell.c
@ -644,7 +644,7 @@ parse (const char *s, size_t len, char **e) {
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// --- Runtime -----------------------------------------------------------------
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struct context;
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typedef bool (*handler_fn) (struct context *);
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typedef bool (*handler_fn) (struct context *, struct item *, struct item **);
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struct native_fn {
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struct native_fn *next; ///< The next link in the chain
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@ -696,6 +696,42 @@ context_free (struct context *ctx) {
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free (ctx->error);
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}
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static struct item *
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get (struct context *ctx, const char *name) {
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for (struct item *iter = ctx->variables; iter; iter = iter->next)
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if (!strcmp (iter->head->value, name))
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return iter->head->next;
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return NULL;
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}
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// FIXME: cloning and removing
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static bool
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set (struct context *ctx, const char *name, struct item *value) {
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struct item *iter, *key = NULL, *pair = NULL;
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for (iter = ctx->variables; iter; iter = iter->next)
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if (!strcmp (iter->head->value, name))
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break;
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if (iter) {
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item_free (iter->head->next);
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iter->head->next = value;
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return true;
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}
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if ((key = new_string (name, strlen (name)))
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&& (pair = new_list (NULL))) {
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(pair->head = key)->next = value;
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pair->next = ctx->variables;
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ctx->variables = pair;
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return true;
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} else {
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item_free_list (key);
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item_free_list (pair);
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ctx->memory_failure = true;
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return false;
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}
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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static bool
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set_error (struct context *ctx, const char *format, ...) {
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free (ctx->error);
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@ -710,48 +746,106 @@ set_error (struct context *ctx, const char *format, ...) {
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return false;
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}
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static struct item *
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var (struct context *ctx, const char *name) {
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for (struct item *iter = ctx->variables; iter; iter = iter->next)
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if (!strcmp (iter->head->value, name))
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return iter->head->next;
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return NULL;
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}
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static void
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set (struct context *ctx, const char *name, struct item *value) {
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for (struct item *iter = ctx->variables; iter; iter = iter->next)
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if (!strcmp (iter->head->value, name)) {
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item_free (iter->head->next);
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iter->head->next = value;
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return;
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}
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struct item *key = new_string (name, strlen (name));
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key->next = value;
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struct item *pair = new_list (key);
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pair->next = ctx->variables;
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ctx->variables = pair;
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}
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static struct item *execute (struct context *, struct item *);
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static bool
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call_function (struct context *ctx, const char *name) {
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struct item *body = var (ctx, name);
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if (!body) {
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struct native_fn *fn;
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for (fn = g_native; fn; fn = fn->next)
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if (!strcmp (name, fn->name))
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break;
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if (!fn)
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return set_error (ctx, "unknown function: %s", name);
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if (fn->handler (ctx))
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rename_arguments (struct context *ctx, struct item *names) {
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size_t i = 0;
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for (; names; names = names->next) {
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char buf[64];
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(void) snprintf (buf, sizeof buf, "%zu", i++);
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struct item *value = get (ctx, buf);
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if (names->type != ITEM_STRING)
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continue;
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if (value)
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set (ctx, names->value, new_clone (value));
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else
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set (ctx, names->value, NULL);
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}
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return true;
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}
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static bool execute (struct context *ctx, struct item *body, struct item **);
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// TODO: we should probably maintain arguments in a separate list,
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// either that or at least remember the count so that we can reset them
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static bool
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execute_statement
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(struct context *ctx, struct item *statement, struct item **result) {
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if (statement->type == ITEM_STRING) {
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if ((*result = new_clone (statement)))
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return true;
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} else if (body->type == ITEM_STRING) {
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return set_error (ctx, "strings aren't callable: %s", name);
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} else if (execute (ctx, body))
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ctx->memory_failure = true;
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return false;
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}
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// XXX: should this ever happen and what are the consequences?
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// Shouldn't we rather clone the empty list?
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struct item *body;
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if (!(body = statement->head))
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return true;
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const char *name = "(anonymous)";
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if (body->type == ITEM_STRING) {
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name = body->value;
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if (!strcmp (name, "quote")) {
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if ((*result = new_clone_list (body->next)))
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return true;
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ctx->memory_failure = true;
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return false;
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}
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if (!strcmp (name, "arg"))
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return rename_arguments (ctx, body->next);
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if (!(body = get (ctx, body->value))) {
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struct native_fn *fn;
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for (fn = g_native; fn; fn = fn->next)
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if (!strcmp (name, fn->name))
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break;
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if (!fn)
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return set_error (ctx, "unknown function: %s", name);
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struct item *args = NULL, **tail = &args;
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for (struct item *arg = statement->head->next;
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arg; arg = arg->next) {
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struct item *evaluated = NULL;
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if (!execute_statement (ctx, arg, &evaluated))
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return false;
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if (evaluated) {
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item_free_list (evaluated->next);
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evaluated->next = NULL;
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*tail = evaluated;
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tail = &evaluated->next;
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}
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}
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bool ok = fn->handler (ctx, args, result);
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item_free_list (args);
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if (ok)
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return true;
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goto error;
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}
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}
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// Recursion could be pretty fatal, let's not do that
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if (body->type == ITEM_STRING)
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return new_clone (body);
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size_t i = 0;
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for (struct item *arg = statement->head->next; arg; arg = arg->next) {
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struct item *evaluated = NULL;
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if (!execute_statement (ctx, arg, &evaluated))
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return false;
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item_free_list (evaluated->next);
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evaluated->next = NULL;
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char buf[64];
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(void) snprintf (buf, sizeof buf, "%zu", i++);
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set (ctx, buf, evaluated);
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}
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if (execute (ctx, body->head, result))
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return true;
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error:
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// In this case, `error' is NULL
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if (ctx->memory_failure)
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return false;
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@ -764,55 +858,32 @@ call_function (struct context *ctx, const char *name) {
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return false;
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}
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static struct item *execute (struct context *ctx, struct item *script);
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static struct item *
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execute_one (struct context *ctx, struct item *statement) {
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if (!statement->head)
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return NULL;
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struct item *fn = statement->head->head;
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if (statement->head->type == ITEM_STRING) {
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if (!strcmp (statement->head->value, "quote")) {
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return statement->head->next;
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} else if (!strcmp (statement->head->value, "arg")) {
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// TODO: rename \d+ variables to arguments
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} else {
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// TODO: resolve the string
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fn = NULL;
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}
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}
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// TODO: assign the rest of items to variables
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return execute (ctx, fn);
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}
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// Execute a block and return whatever the last statement returned
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static struct item *
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execute (struct context *ctx, struct item *script) {
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struct item *result = NULL;
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for (; script; script = script->next) {
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assert (script->type == ITEM_LIST);
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item_free_list (result);
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result = execute_one (ctx, script);
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static bool
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execute (struct context *ctx, struct item *body, struct item **result) {
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for (; body; body = body->next) {
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item_free_list (*result);
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*result = NULL;
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if (!execute_statement (ctx, body, result))
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return false;
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}
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return result;
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return true;
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}
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// --- Runtime library ---------------------------------------------------------
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#define defn(name) static bool name (struct context *ctx)
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#define defn(name) static bool name \
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(struct context *ctx, struct item *args, struct item **result)
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static bool
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init_runtime_library_scripts (struct context *ctx) {
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bool ok = true;
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// It's much cheaper (and more fun) to define functions in terms of other
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// ones. The "unit tests" serve a secondary purpose of showing the usage.
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struct {
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const char *name; ///< Name of the function
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const char *definition; ///< The defining script
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} functions[] = {
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{ "greet", "arg _name\n" "print (.. 'hello ' (.. @_name))" },
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{ "greet", "arg _name\n" "print (.. 'hello ' @_name '\\n')" },
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};
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for (size_t i = 0; i < N_ELEMENTS (functions); i++) {
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@ -830,9 +901,25 @@ init_runtime_library_scripts (struct context *ctx) {
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return ok;
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}
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defn (fn_set) {
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struct item *name = args;
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if (!name || name->type != ITEM_STRING)
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return (void *) set_error (ctx, "first argument must be string");
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struct item *value;
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if ((value = name->next))
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return set (ctx, name->value, value);
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// FIXME: how do we represent a nil value here?
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*result = get (ctx, name->value);
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return true;
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}
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defn (fn_print) {
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(void) result;
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struct buffer buf = BUFFER_INITIALIZER;
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struct item *item = var (ctx, "1");
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struct item *item = args;
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buffer_append (&buf, item->value, item->len);
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buffer_append_c (&buf, '\0');
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if (buf.memory_failure) {
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@ -846,7 +933,17 @@ defn (fn_print) {
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}
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defn (fn_concatenate) {
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// TODO: concatenate string arguments, error on list
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// TODO: error on list
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struct buffer buf = BUFFER_INITIALIZER;
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for (; args; args = args->next)
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buffer_append (&buf, args->value, args->len);
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buffer_append_c (&buf, '\0');
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if (buf.memory_failure) {
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ctx->memory_failure = true;
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return false;
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}
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*result = new_string (buf.s, buf.len);
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free (buf.s);
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return true;
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}
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@ -854,6 +951,7 @@ static bool
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init_runtime_library (void)
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{
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return register_native ("..", fn_concatenate)
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&& register_native ("set", fn_set)
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&& register_native ("print", fn_print);
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}
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@ -871,7 +969,7 @@ free_runtime_library (void) {
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int
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main (int argc, char *argv[]) {
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// TODO: load the entirety of stdin
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const char *program = "print 'hello world\\n'";
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const char *program = "greet 'world'";
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char *e = NULL;
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struct item *tree = parse (program, strlen (program), &e);
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@ -887,7 +985,9 @@ main (int argc, char *argv[]) {
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|| !init_runtime_library_scripts (&ctx))
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printf ("%s\n", "runtime library initialization failed");
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ctx.user_data = NULL;
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item_free_list (execute (&ctx, tree));
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struct item *result = NULL;
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(void) execute (&ctx, tree->head, &result);
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item_free_list (result);
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item_free_list (tree);
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const char *failure = NULL;
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