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-rwxr-xr-xplugins/xB/script2310
1 files changed, 2310 insertions, 0 deletions
diff --git a/plugins/xB/script b/plugins/xB/script
new file mode 100755
index 0000000..43bd66f
--- /dev/null
+++ b/plugins/xB/script
@@ -0,0 +1,2310 @@
+#!/usr/bin/tcc -run -lm
+//
+// xB scripting plugin, using a custom stack-based language
+//
+// Copyright 2014 Přemysl Eric Janouch
+// See the file LICENSE for licensing information.
+//
+// Just compile this file as usual (sans #!) if you don't feel like using TCC.
+// It is a very basic and portable C99 application. It's not supposed to be
+// very sophisticated, for it'd get extremely big.
+//
+// The main influences of the language were Factor and Joy, stripped of all
+// even barely complex stuff. In its current state, it's only really useful as
+// a calculator but it's got great potential for extending.
+//
+// If you don't like something, just change it; this is just an experiment.
+//
+// NOTE: it is relatively easy to abuse. Be careful.
+//
+
+#define _XOPEN_SOURCE 500
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+#include <errno.h>
+#include <stdarg.h>
+#include <assert.h>
+#include <time.h>
+#include <stdbool.h>
+#include <strings.h>
+#include <math.h>
+
+#define ADDRESS_SPACE_LIMIT (100 * 1024 * 1024)
+#include <sys/resource.h>
+
+#if defined __GNUC__
+#define ATTRIBUTE_PRINTF(x, y) __attribute__ ((format (printf, x, y)))
+#else // ! __GNUC__
+#define ATTRIBUTE_PRINTF(x, y)
+#endif // ! __GNUC__
+
+#define N_ELEMENTS(a) (sizeof (a) / sizeof ((a)[0]))
+
+// --- Utilities ---------------------------------------------------------------
+
+static char *strdup_printf (const char *format, ...) ATTRIBUTE_PRINTF (1, 2);
+
+static char *
+strdup_vprintf (const char *format, va_list ap)
+{
+ va_list aq;
+ va_copy (aq, ap);
+ int size = vsnprintf (NULL, 0, format, aq);
+ va_end (aq);
+ if (size < 0)
+ return NULL;
+
+ char buf[size + 1];
+ size = vsnprintf (buf, sizeof buf, format, ap);
+ if (size < 0)
+ return NULL;
+
+ return strdup (buf);
+}
+
+static char *
+strdup_printf (const char *format, ...)
+{
+ va_list ap;
+ va_start (ap, format);
+ char *result = strdup_vprintf (format, ap);
+ va_end (ap);
+ return result;
+}
+
+// --- Generic buffer ----------------------------------------------------------
+
+struct buffer
+{
+ char *s; ///< Buffer data
+ size_t alloc; ///< Number of bytes allocated
+ size_t len; ///< Number of bytes used
+ bool memory_failure; ///< Memory allocation failed
+};
+
+#define BUFFER_INITIALIZER { NULL, 0, 0, false }
+
+static bool
+buffer_append (struct buffer *self, const void *s, size_t n)
+{
+ if (self->memory_failure)
+ return false;
+
+ if (!self->s)
+ self->s = malloc (self->alloc = 8);
+ while (self->len + n > self->alloc)
+ self->s = realloc (self->s, self->alloc <<= 1);
+
+ if (!self->s)
+ {
+ self->memory_failure = true;
+ return false;
+ }
+
+ memcpy (self->s + self->len, s, n);
+ self->len += n;
+ return true;
+}
+
+inline static bool
+buffer_append_c (struct buffer *self, char c)
+{
+ return buffer_append (self, &c, 1);
+}
+
+// --- Data types --------------------------------------------------------------
+
+enum item_type
+{
+ ITEM_STRING,
+ ITEM_WORD,
+ ITEM_INTEGER,
+ ITEM_FLOAT,
+ ITEM_LIST
+};
+
+struct item
+{
+#define ITEM_HEADER \
+ enum item_type type; /**< The type of this object */ \
+ struct item *next; /**< Next item on the list/stack */
+
+ ITEM_HEADER
+};
+
+struct item_string
+{
+ ITEM_HEADER
+ size_t len; ///< Length of the string (sans '\0')
+ char value[]; ///< The null-terminated string value
+};
+
+#define get_string(item) \
+ (assert ((item)->type == ITEM_STRING), \
+ ((struct item_string *)(item))->value)
+
+/// It looks like a string but it doesn't quack like a string
+#define item_word item_string
+
+#define get_word(item) \
+ (assert ((item)->type == ITEM_WORD), \
+ ((struct item_word *)(item))->value)
+
+struct item_integer
+{
+ ITEM_HEADER
+ long long value; ///< The integer value
+};
+
+#define get_integer(item) \
+ (assert ((item)->type == ITEM_INTEGER), \
+ ((struct item_integer *)(item))->value)
+
+struct item_float
+{
+ ITEM_HEADER
+ long double value; ///< The floating point value
+};
+
+#define get_float(item) \
+ (assert ((item)->type == ITEM_FLOAT), \
+ ((struct item_float *)(item))->value)
+
+struct item_list
+{
+ ITEM_HEADER
+ struct item *head; ///< The head of the list
+};
+
+#define get_list(item) \
+ (assert ((item)->type == ITEM_LIST), \
+ ((struct item_list *)(item))->head)
+
+#define set_list(item, head_) \
+ (assert ((item)->type == ITEM_LIST), \
+ item_free_list (((struct item_list *)(item))->head), \
+ ((struct item_list *)(item))->head = (head_))
+
+const char *
+item_type_to_str (enum item_type type)
+{
+ switch (type)
+ {
+ case ITEM_STRING: return "string";
+ case ITEM_WORD: return "word";
+ case ITEM_INTEGER: return "integer";
+ case ITEM_FLOAT: return "float";
+ case ITEM_LIST: return "list";
+ }
+ abort ();
+}
+
+// --- Item management ---------------------------------------------------------
+
+static void item_free_list (struct item *);
+static struct item *new_clone_list (const struct item *);
+
+static void
+item_free (struct item *item)
+{
+ if (item->type == ITEM_LIST)
+ item_free_list (get_list (item));
+ free (item);
+}
+
+static void
+item_free_list (struct item *item)
+{
+ while (item)
+ {
+ struct item *link = item;
+ item = item->next;
+ item_free (link);
+ }
+}
+
+static struct item *
+new_clone (const struct item *item)
+{
+ size_t size;
+ switch (item->type)
+ {
+ case ITEM_STRING:
+ case ITEM_WORD:
+ {
+ const struct item_string *x = (const struct item_string *) item;
+ size = sizeof *x + x->len + 1;
+ break;
+ }
+ case ITEM_INTEGER: size = sizeof (struct item_integer); break;
+ case ITEM_FLOAT: size = sizeof (struct item_float); break;
+ case ITEM_LIST: size = sizeof (struct item_list); break;
+ }
+
+ struct item *clone = malloc (size);
+ if (!clone)
+ return NULL;
+
+ memcpy (clone, item, size);
+ if (item->type == ITEM_LIST)
+ {
+ struct item_list *x = (struct item_list *) clone;
+ if (x->head && !(x->head = new_clone_list (x->head)))
+ {
+ free (clone);
+ return NULL;
+ }
+ }
+ clone->next = NULL;
+ return clone;
+}
+
+static struct item *
+new_clone_list (const struct item *item)
+{
+ struct item *head = NULL, *clone;
+ for (struct item **out = &head; item; item = item->next)
+ {
+ if (!(clone = *out = new_clone (item)))
+ {
+ item_free_list (head);
+ return NULL;
+ }
+ clone->next = NULL;
+ out = &clone->next;
+ }
+ return head;
+}
+
+static struct item *
+new_string (const char *s, ssize_t len)
+{
+ if (len < 0)
+ len = strlen (s);
+
+ struct item_string *item = calloc (1, sizeof *item + len + 1);
+ if (!item)
+ return NULL;
+
+ item->type = ITEM_STRING;
+ item->len = len;
+ memcpy (item->value, s, len);
+ item->value[len] = '\0';
+ return (struct item *) item;
+}
+
+static struct item *
+new_word (const char *s, ssize_t len)
+{
+ struct item *item = new_string (s, len);
+ if (!item)
+ return NULL;
+
+ item->type = ITEM_WORD;
+ return item;
+}
+
+static struct item *
+new_integer (long long value)
+{
+ struct item_integer *item = calloc (1, sizeof *item);
+ if (!item)
+ return NULL;
+
+ item->type = ITEM_INTEGER;
+ item->value = value;
+ return (struct item *) item;
+}
+
+static struct item *
+new_float (long double value)
+{
+ struct item_float *item = calloc (1, sizeof *item);
+ if (!item)
+ return NULL;
+
+ item->type = ITEM_FLOAT;
+ item->value = value;
+ return (struct item *) item;
+}
+
+static struct item *
+new_list (struct item *head)
+{
+ struct item_list *item = calloc (1, sizeof *item);
+ if (!item)
+ return NULL;
+
+ item->type = ITEM_LIST;
+ item->head = head;
+ return (struct item *) item;
+}
+
+// --- Parsing -----------------------------------------------------------------
+
+#define PARSE_ERROR_TABLE(XX) \
+ XX( OK, NULL ) \
+ XX( EOF, "unexpected end of input" ) \
+ XX( INVALID_HEXA_ESCAPE, "invalid hexadecimal escape sequence" ) \
+ XX( INVALID_ESCAPE, "unrecognized escape sequence" ) \
+ XX( MEMORY, "memory allocation failure" ) \
+ XX( FLOAT_RANGE, "floating point value out of range" ) \
+ XX( INTEGER_RANGE, "integer out of range" ) \
+ XX( INVALID_INPUT, "invalid input" ) \
+ XX( UNEXPECTED_INPUT, "unexpected input" )
+
+enum tokenizer_error
+{
+#define XX(x, y) PARSE_ERROR_ ## x,
+ PARSE_ERROR_TABLE (XX)
+#undef XX
+ PARSE_ERROR_COUNT
+};
+
+struct tokenizer
+{
+ const char *cursor;
+ enum tokenizer_error error;
+};
+
+static bool
+decode_hexa_escape (struct tokenizer *self, struct buffer *buf)
+{
+ int i;
+ char c, code = 0;
+
+ for (i = 0; i < 2; i++)
+ {
+ c = tolower (*self->cursor);
+ if (c >= '0' && c <= '9')
+ code = (code << 4) | (c - '0');
+ else if (c >= 'a' && c <= 'f')
+ code = (code << 4) | (c - 'a' + 10);
+ else
+ break;
+
+ self->cursor++;
+ }
+
+ if (!i)
+ return false;
+
+ buffer_append_c (buf, code);
+ return true;
+}
+
+static bool
+decode_octal_escape (struct tokenizer *self, struct buffer *buf)
+{
+ int i;
+ char c, code = 0;
+
+ for (i = 0; i < 3; i++)
+ {
+ c = *self->cursor;
+ if (c < '0' || c > '7')
+ break;
+
+ code = (code << 3) | (c - '0');
+ self->cursor++;
+ }
+
+ if (!i)
+ return false;
+
+ buffer_append_c (buf, code);
+ return true;
+}
+
+static bool
+decode_escape_sequence (struct tokenizer *self, struct buffer *buf)
+{
+ // Support some basic escape sequences from the C language
+ char c;
+ switch ((c = *self->cursor))
+ {
+ case '\0':
+ self->error = PARSE_ERROR_EOF;
+ return false;
+ case 'x':
+ case 'X':
+ self->cursor++;
+ if (decode_hexa_escape (self, buf))
+ return true;
+
+ self->error = PARSE_ERROR_INVALID_HEXA_ESCAPE;
+ return false;
+ default:
+ if (decode_octal_escape (self, buf))
+ return true;
+
+ self->cursor++;
+ const char *from = "abfnrtv\"\\", *to = "\a\b\f\n\r\t\v\"\\", *x;
+ if ((x = strchr (from, c)))
+ {
+ buffer_append_c (buf, to[x - from]);
+ return true;
+ }
+
+ self->error = PARSE_ERROR_INVALID_ESCAPE;
+ return false;
+ }
+}
+
+static struct item *
+parse_string (struct tokenizer *self)
+{
+ struct buffer buf = BUFFER_INITIALIZER;
+ struct item *item = NULL;
+ char c;
+
+ while (true)
+ switch ((c = *self->cursor++))
+ {
+ case '\0':
+ self->cursor--;
+ self->error = PARSE_ERROR_EOF;
+ goto end;
+ case '"':
+ if (buf.memory_failure
+ || !(item = new_string (buf.s, buf.len)))
+ self->error = PARSE_ERROR_MEMORY;
+ goto end;
+ case '\\':
+ if (decode_escape_sequence (self, &buf))
+ break;
+ goto end;
+ default:
+ buffer_append_c (&buf, c);
+ }
+
+end:
+ free (buf.s);
+ return item;
+}
+
+static struct item *
+try_parse_number (struct tokenizer *self)
+{
+ // These two standard library functions can digest a lot of various inputs,
+ // including NaN and +/- infinity. That may get a bit confusing.
+ char *float_end;
+ errno = 0;
+ long double float_value = strtold (self->cursor, &float_end);
+ int float_errno = errno;
+
+ char *int_end;
+ errno = 0;
+ long long int_value = strtoll (self->cursor, &int_end, 10);
+ int int_errno = errno;
+
+ // If they both fail, then this is most probably not a number.
+ if (float_end == int_end && float_end == self->cursor)
+ return NULL;
+
+ // Only use the floating point result if it parses more characters:
+ struct item *item;
+ if (float_end > int_end)
+ {
+ if (float_errno == ERANGE)
+ {
+ self->error = PARSE_ERROR_FLOAT_RANGE;
+ return NULL;
+ }
+ self->cursor = float_end;
+ if (!(item = new_float (float_value)))
+ self->error = PARSE_ERROR_MEMORY;
+ return item;
+ }
+ else
+ {
+ if (int_errno == ERANGE)
+ {
+ self->error = PARSE_ERROR_INTEGER_RANGE;
+ return NULL;
+ }
+ self->cursor = int_end;
+ if (!(item = new_integer (int_value)))
+ self->error = PARSE_ERROR_MEMORY;
+ return item;
+ }
+}
+
+static struct item *
+parse_word (struct tokenizer *self)
+{
+ struct buffer buf = BUFFER_INITIALIZER;
+ struct item *item = NULL;
+ char c;
+
+ // Here we accept almost anything that doesn't break the grammar
+ while (!strchr (" []\"", (c = *self->cursor++)) && (unsigned char) c > ' ')
+ buffer_append_c (&buf, c);
+ self->cursor--;
+
+ if (buf.memory_failure)
+ self->error = PARSE_ERROR_MEMORY;
+ else if (!buf.len)
+ self->error = PARSE_ERROR_INVALID_INPUT;
+ else if (!(item = new_word (buf.s, buf.len)))
+ self->error = PARSE_ERROR_MEMORY;
+
+ free (buf.s);
+ return item;
+}
+
+static struct item *parse_item_list (struct tokenizer *);
+
+static struct item *
+parse_list (struct tokenizer *self)
+{
+ struct item *list = parse_item_list (self);
+ if (self->error)
+ {
+ assert (list == NULL);
+ return NULL;
+ }
+ if (!*self->cursor)
+ {
+ self->error = PARSE_ERROR_EOF;
+ item_free_list (list);
+ return NULL;
+ }
+ assert (*self->cursor == ']');
+ self->cursor++;
+ return new_list (list);
+}
+
+static struct item *
+parse_item (struct tokenizer *self)
+{
+ char c;
+ switch ((c = *self->cursor++))
+ {
+ case '[': return parse_list (self);
+ case '"': return parse_string (self);
+ default:;
+ }
+
+ self->cursor--;
+ struct item *item = try_parse_number (self);
+ if (!item && !self->error)
+ item = parse_word (self);
+ return item;
+}
+
+static struct item *
+parse_item_list (struct tokenizer *self)
+{
+ struct item *head = NULL;
+ struct item **tail = &head;
+
+ char c;
+ bool expected = true;
+ while ((c = *self->cursor) && c != ']')
+ {
+ if (isspace (c))
+ {
+ self->cursor++;
+ expected = true;
+ continue;
+ }
+ else if (!expected)
+ {
+ self->error = PARSE_ERROR_UNEXPECTED_INPUT;
+ goto fail;
+ }
+
+ if (!(*tail = parse_item (self)))
+ goto fail;
+ tail = &(*tail)->next;
+ expected = false;
+ }
+ return head;
+
+fail:
+ item_free_list (head);
+ return NULL;
+}
+
+static struct item *
+parse (const char *s, const char **error)
+{
+ struct tokenizer self = { .cursor = s, .error = PARSE_ERROR_OK };
+ struct item *list = parse_item_list (&self);
+ if (!self.error && *self.cursor != '\0')
+ {
+ self.error = PARSE_ERROR_UNEXPECTED_INPUT;
+ item_free_list (list);
+ list = NULL;
+ }
+
+#define XX(x, y) y,
+ static const char *strings[PARSE_ERROR_COUNT] =
+ { PARSE_ERROR_TABLE (XX) };
+#undef XX
+
+ static char error_buf[128];
+ if (self.error && error)
+ {
+ snprintf (error_buf, sizeof error_buf, "at character %d: %s",
+ (int) (self.cursor - s) + 1, strings[self.error]);
+ *error = error_buf;
+ }
+ return list;
+}
+
+// --- Runtime -----------------------------------------------------------------
+
+// TODO: try to think of a _simple_ way to do preemptive multitasking
+
+struct context
+{
+ struct item *stack; ///< The current top of the stack
+ size_t stack_size; ///< Number of items on the stack
+
+ size_t reduction_count; ///< # of function calls so far
+ size_t reduction_limit; ///< The hard limit on function calls
+
+ char *error; ///< Error information
+ bool error_is_fatal; ///< Whether the error can be catched
+ bool memory_failure; ///< Memory allocation failure
+
+ void *user_data; ///< User data
+};
+
+/// Internal handler for a function
+typedef bool (*handler_fn) (struct context *);
+
+struct fn
+{
+ struct fn *next; ///< The next link in the chain
+
+ handler_fn handler; ///< Internal C handler, or NULL
+ struct item *script; ///< Alternatively runtime code
+ char name[]; ///< The name of the function
+};
+
+struct fn *g_functions; ///< Maps words to functions
+
+static void
+context_init (struct context *ctx)
+{
+ ctx->stack = NULL;
+ ctx->stack_size = 0;
+
+ ctx->reduction_count = 0;
+ ctx->reduction_limit = 2000;
+
+ ctx->error = NULL;
+ ctx->error_is_fatal = false;
+ ctx->memory_failure = false;
+
+ ctx->user_data = NULL;
+}
+
+static void
+context_free (struct context *ctx)
+{
+ item_free_list (ctx->stack);
+ ctx->stack = NULL;
+
+ free (ctx->error);
+ ctx->error = NULL;
+}
+
+static bool
+set_error (struct context *ctx, const char *format, ...)
+{
+ free (ctx->error);
+
+ va_list ap;
+ va_start (ap, format);
+ ctx->error = strdup_vprintf (format, ap);
+ va_end (ap);
+
+ if (!ctx->error)
+ ctx->memory_failure = true;
+ return false;
+}
+
+static bool
+push (struct context *ctx, struct item *item)
+{
+ // The `item' is typically a result from new_<type>(), thus when it is null,
+ // that function must have failed. This is a shortcut for convenience.
+ if (!item)
+ {
+ ctx->memory_failure = true;
+ return false;
+ }
+
+ assert (item->next == NULL);
+ item->next = ctx->stack;
+ ctx->stack = item;
+ ctx->stack_size++;
+ return true;
+}
+
+static bool
+bump_reductions (struct context *ctx)
+{
+ if (++ctx->reduction_count >= ctx->reduction_limit)
+ {
+ ctx->error_is_fatal = true;
+ return set_error (ctx, "reduction limit reached");
+ }
+ return true;
+}
+
+static bool execute (struct context *, struct item *);
+
+static bool
+call_function (struct context *ctx, const char *name)
+{
+ struct fn *iter;
+ for (iter = g_functions; iter; iter = iter->next)
+ if (!strcmp (name, iter->name))
+ goto found;
+ return set_error (ctx, "unknown function: %s", name);
+
+found:
+ if (!bump_reductions (ctx))
+ return false;
+
+ if (iter->handler
+ ? iter->handler (ctx)
+ : execute (ctx, iter->script))
+ return true;
+
+ // In this case, `error' is NULL
+ if (ctx->memory_failure)
+ return false;
+
+ // This creates some form of a stack trace
+ char *tmp = ctx->error;
+ ctx->error = NULL;
+ set_error (ctx, "%s -> %s", name, tmp);
+ free (tmp);
+ return false;
+}
+
+static void
+free_function (struct fn *fn)
+{
+ item_free_list (fn->script);
+ free (fn);
+}
+
+static void
+unregister_function (const char *name)
+{
+ for (struct fn **iter = &g_functions; *iter; iter = &(*iter)->next)
+ if (!strcmp ((*iter)->name, name))
+ {
+ struct fn *tmp = *iter;
+ *iter = tmp->next;
+ free_function (tmp);
+ break;
+ }
+}
+
+static struct fn *
+prepend_new_fn (const char *name)
+{
+ struct fn *fn = calloc (1, sizeof *fn + strlen (name) + 1);
+ if (!fn)
+ return NULL;
+
+ strcpy (fn->name, name);
+ fn->next = g_functions;
+ return g_functions = fn;
+}
+
+static bool
+register_handler (const char *name, handler_fn handler)
+{
+ unregister_function (name);
+ struct fn *fn = prepend_new_fn (name);
+ if (!fn)
+ return false;
+ fn->handler = handler;
+ return true;
+}
+
+static bool
+register_script (const char *name, struct item *script)
+{
+ unregister_function (name);
+ struct fn *fn = prepend_new_fn (name);
+ if (!fn)
+ return false;
+ fn->script = script;
+ return true;
+}
+
+static bool
+execute (struct context *ctx, struct item *script)
+{
+ for (; script; script = script->next)
+ {
+ if (script->type != ITEM_WORD)
+ {
+ if (!bump_reductions (ctx)
+ || !push (ctx, new_clone (script)))
+ return false;
+ }
+ else if (!call_function (ctx, get_word (script)))
+ return false;
+ }
+ return true;
+}
+
+// --- Runtime library ---------------------------------------------------------
+
+#define defn(name) static bool name (struct context *ctx)
+
+#define check_stack(n) \
+ if (ctx->stack_size < n) { \
+ set_error (ctx, "stack underflow"); \
+ return 0; \
+ }
+
+inline static bool
+check_stack_safe (struct context *ctx, size_t n)
+{
+ check_stack (n);
+ return true;
+}
+
+static bool
+check_type (struct context *ctx, const void *item_, enum item_type type)
+{
+ const struct item *item = item_;
+ if (item->type == type)
+ return true;
+
+ return set_error (ctx, "invalid type: expected `%s', got `%s'",
+ item_type_to_str (type), item_type_to_str (item->type));
+}
+
+static struct item *
+pop (struct context *ctx)
+{
+ check_stack (1);
+ struct item *top = ctx->stack;
+ ctx->stack = top->next;
+ top->next = NULL;
+ ctx->stack_size--;
+ return top;
+}
+
+// - - Types - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+#define defn_is_type(name, item_type) \
+ defn (fn_is_##name) { \
+ check_stack (1); \
+ struct item *top = pop (ctx); \
+ push (ctx, new_integer (top->type == (item_type))); \
+ item_free (top); \
+ return true; \
+ }
+
+defn_is_type (string, ITEM_STRING)
+defn_is_type (word, ITEM_WORD)
+defn_is_type (integer, ITEM_INTEGER)
+defn_is_type (float, ITEM_FLOAT)
+defn_is_type (list, ITEM_LIST)
+
+defn (fn_to_string)
+{
+ check_stack (1);
+ struct item *item = pop (ctx);
+ char *value;
+
+ switch (item->type)
+ {
+ case ITEM_WORD:
+ item->type = ITEM_STRING;
+ case ITEM_STRING:
+ return push (ctx, item);
+
+ case ITEM_FLOAT:
+ value = strdup_printf ("%Lf", get_float (item));
+ break;
+ case ITEM_INTEGER:
+ value = strdup_printf ("%lld", get_integer (item));
+ break;
+
+ default:
+ set_error (ctx, "cannot convert `%s' to `%s'",
+ item_type_to_str (item->type), item_type_to_str (ITEM_STRING));
+ item_free (item);
+ return false;
+ }
+
+ item_free (item);
+ if (!value)
+ {
+ ctx->memory_failure = true;
+ return false;
+ }
+
+ item = new_string (value, -1);
+ free (value);
+ return push (ctx, item);
+}
+
+defn (fn_to_integer)
+{
+ check_stack (1);
+ struct item *item = pop (ctx);
+ long long value;
+
+ switch (item->type)
+ {
+ case ITEM_INTEGER:
+ return push (ctx, item);
+ case ITEM_FLOAT:
+ value = get_float (item);
+ break;
+
+ case ITEM_STRING:
+ {
+ char *end;
+ const char *s = get_string (item);
+ value = strtoll (s, &end, 10);
+ if (end != s && *s == '\0')
+ break;
+
+ item_free (item);
+ return set_error (ctx, "integer conversion error");
+ }
+
+ default:
+ set_error (ctx, "cannot convert `%s' to `%s'",
+ item_type_to_str (item->type), item_type_to_str (ITEM_INTEGER));
+ item_free (item);
+ return false;
+ }
+
+ item_free (item);
+ return push (ctx, new_integer (value));
+}
+
+defn (fn_to_float)
+{
+ check_stack (1);
+ struct item *item = pop (ctx);
+ long double value;
+
+ switch (item->type)
+ {
+ case ITEM_FLOAT:
+ return push (ctx, item);
+ case ITEM_INTEGER:
+ value = get_integer (item);
+ break;
+
+ case ITEM_STRING:
+ {
+ char *end;
+ const char *s = get_string (item);
+ value = strtold (s, &end);
+ if (end != s && *s == '\0')
+ break;
+
+ item_free (item);
+ return set_error (ctx, "float conversion error");
+ }
+
+ default:
+ set_error (ctx, "cannot convert `%s' to `%s'",
+ item_type_to_str (item->type), item_type_to_str (ITEM_FLOAT));
+ item_free (item);
+ return false;
+ }
+
+ item_free (item);
+ return push (ctx, new_float (value));
+}
+
+// - - Miscellaneous - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+defn (fn_length)
+{
+ check_stack (1);
+ struct item *item = pop (ctx);
+ bool success = true;
+ switch (item->type)
+ {
+ case ITEM_STRING:
+ success = push (ctx, new_integer (((struct item_string *) item)->len));
+ break;
+ case ITEM_LIST:
+ {
+ long long length = 0;
+ struct item *iter;
+ for (iter = get_list (item); iter; iter = iter->next)
+ length++;
+ success = push (ctx, new_integer (length));
+ break;
+ }
+ default:
+ success = set_error (ctx, "invalid type");
+ }
+ item_free (item);
+ return success;
+}
+
+// - - Stack operations - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+defn (fn_dup)
+{
+ check_stack (1);
+ return push (ctx, new_clone (ctx->stack));
+}
+
+defn (fn_drop)
+{
+ check_stack (1);
+ item_free (pop (ctx));
+ return true;
+}
+
+defn (fn_swap)
+{
+ check_stack (2);
+ struct item *second = pop (ctx), *first = pop (ctx);
+ return push (ctx, second) && push (ctx, first);
+}
+
+defn (fn_call)
+{
+ check_stack (1);
+ struct item *script = pop (ctx);
+ bool success = check_type (ctx, script, ITEM_LIST)
+ && execute (ctx, get_list (script));
+ item_free (script);
+ return success;
+}
+
+defn (fn_dip)
+{
+ check_stack (2);
+ struct item *script = pop (ctx);
+ struct item *item = pop (ctx);
+ bool success = check_type (ctx, script, ITEM_LIST)
+ && execute (ctx, get_list (script));
+ item_free (script);
+ if (!success)
+ {
+ item_free (item);
+ return false;
+ }
+ return push (ctx, item);
+}
+
+defn (fn_unit)
+{
+ check_stack (1);
+ struct item *item = pop (ctx);
+ return push (ctx, new_list (item));
+}
+
+defn (fn_cons)
+{
+ check_stack (2);
+ struct item *list = pop (ctx);
+ struct item *item = pop (ctx);
+ if (!check_type (ctx, list, ITEM_LIST))
+ {
+ item_free (list);
+ item_free (item);
+ return false;
+ }
+ item->next = get_list (list);
+ ((struct item_list *) list)->head = item;
+ return push (ctx, list);
+}
+
+defn (fn_cat)
+{
+ check_stack (2);
+ struct item *scnd = pop (ctx);
+ struct item *frst = pop (ctx);
+ if (!check_type (ctx, frst, ITEM_LIST)
+ || !check_type (ctx, scnd, ITEM_LIST))
+ {
+ item_free (frst);
+ item_free (scnd);
+ return false;
+ }
+
+ // XXX: we shouldn't have to do this in O(n)
+ struct item **tail = &((struct item_list *) frst)->head;
+ while (*tail)
+ tail = &(*tail)->next;
+ *tail = get_list (scnd);
+
+ ((struct item_list *) scnd)->head = NULL;
+ item_free (scnd);
+ return push (ctx, frst);
+}
+
+defn (fn_uncons)
+{
+ check_stack (1);
+ struct item *list = pop (ctx);
+ if (!check_type (ctx, list, ITEM_LIST))
+ goto fail;
+ struct item *first = get_list (list);
+ if (!first)
+ {
+ set_error (ctx, "list is empty");
+ goto fail;
+ }
+ ((struct item_list *) list)->head = first->next;
+ first->next = NULL;
+ return push (ctx, first) && push (ctx, list);
+fail:
+ item_free (list);
+ return false;
+}
+
+// - - Logical - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+static bool
+to_boolean (struct context *ctx, struct item *item, bool *ok)
+{
+ switch (item->type)
+ {
+ case ITEM_STRING:
+ return *get_string (item) != '\0';
+ case ITEM_INTEGER:
+ return get_integer (item) != 0;
+ case ITEM_FLOAT:
+ return get_float (item) != 0.;
+ default:
+ return (*ok = set_error (ctx, "cannot convert `%s' to boolean",
+ item_type_to_str (item->type)));
+ }
+}
+
+defn (fn_not)
+{
+ check_stack (1);
+ struct item *item = pop (ctx);
+ bool ok = true;
+ bool result = !to_boolean (ctx, item, &ok);
+ item_free (item);
+ return ok && push (ctx, new_integer (result));
+}
+
+defn (fn_and)
+{
+ check_stack (2);
+ struct item *op1 = pop (ctx);
+ struct item *op2 = pop (ctx);
+ bool ok = true;
+ bool result = to_boolean (ctx, op1, &ok) && to_boolean (ctx, op2, &ok);
+ item_free (op1);
+ item_free (op2);
+ return ok && push (ctx, new_integer (result));
+}
+
+defn (fn_or)
+{
+ check_stack (2);
+ struct item *op1 = pop (ctx);
+ struct item *op2 = pop (ctx);
+ bool ok = true;
+ bool result = to_boolean (ctx, op1, &ok)
+ || !ok || to_boolean (ctx, op2, &ok);
+ item_free (op1);
+ item_free (op2);
+ return ok && push (ctx, new_integer (result));
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+defn (fn_if)
+{
+ check_stack (3);
+ struct item *else_ = pop (ctx);
+ struct item *then_ = pop (ctx);
+ struct item *cond_ = pop (ctx);
+
+ bool ok = true;
+ bool condition = to_boolean (ctx, cond_, &ok);
+ item_free (cond_);
+
+ bool success = false;
+ if (ok
+ && check_type (ctx, then_, ITEM_LIST)
+ && check_type (ctx, else_, ITEM_LIST))
+ success = execute (ctx, condition
+ ? get_list (then_)
+ : get_list (else_));
+
+ item_free (then_);
+ item_free (else_);
+ return success;
+}
+
+defn (fn_try)
+{
+ check_stack (2);
+ struct item *catch = pop (ctx);
+ struct item *try = pop (ctx);
+ bool success = false;
+ if (!check_type (ctx, try, ITEM_LIST)
+ || !check_type (ctx, catch, ITEM_LIST))
+ goto fail;
+
+ if (!execute (ctx, get_list (try)))
+ {
+ if (ctx->memory_failure || ctx->error_is_fatal)
+ goto fail;
+
+ success = push (ctx, new_string (ctx->error, -1));
+ free (ctx->error);
+ ctx->error = NULL;
+
+ if (success)
+ success = execute (ctx, get_list (catch));
+ }
+
+fail:
+ item_free (try);
+ item_free (catch);
+ return success;
+}
+
+defn (fn_map)
+{
+ check_stack (2);
+ struct item *fn = pop (ctx);
+ struct item *list = pop (ctx);
+ if (!check_type (ctx, fn, ITEM_LIST)
+ || !check_type (ctx, list, ITEM_LIST))
+ {
+ item_free (fn);
+ item_free (list);
+ return false;
+ }
+
+ bool success = false;
+ struct item *result = NULL, **tail = &result;
+ for (struct item *iter = get_list (list); iter; iter = iter->next)
+ {
+ if (!push (ctx, new_clone (iter))
+ || !execute (ctx, get_list (fn))
+ || !check_stack_safe (ctx, 1))
+ goto fail;
+
+ struct item *item = pop (ctx);
+ *tail = item;
+ tail = &item->next;
+ }
+ success = true;
+
+fail:
+ set_list (list, result);
+ item_free (fn);
+ if (!success)
+ {
+ item_free (list);
+ return false;
+ }
+ return push (ctx, list);
+}
+
+defn (fn_filter)
+{
+ check_stack (2);
+ struct item *fn = pop (ctx);
+ struct item *list = pop (ctx);
+ if (!check_type (ctx, fn, ITEM_LIST)
+ || !check_type (ctx, list, ITEM_LIST))
+ {
+ item_free (fn);
+ item_free (list);
+ return false;
+ }
+
+ bool success = false;
+ bool ok = true;
+ struct item *result = NULL, **tail = &result;
+ for (struct item *iter = get_list (list); iter; iter = iter->next)
+ {
+ if (!push (ctx, new_clone (iter))
+ || !execute (ctx, get_list (fn))
+ || !check_stack_safe (ctx, 1))
+ goto fail;
+
+ struct item *item = pop (ctx);
+ bool survived = to_boolean (ctx, item, &ok);
+ item_free (item);
+ if (!ok)
+ goto fail;
+ if (!survived)
+ continue;
+
+ if (!(item = new_clone (iter)))
+ goto fail;
+ *tail = item;
+ tail = &item->next;
+ }
+ success = true;
+
+fail:
+ set_list (list, result);
+ item_free (fn);
+ if (!success)
+ {
+ item_free (list);
+ return false;
+ }
+ return push (ctx, list);
+}
+
+defn (fn_fold)
+{
+ check_stack (3);
+ struct item *op = pop (ctx);
+ struct item *null = pop (ctx);
+ struct item *list = pop (ctx);
+ bool success = false;
+ if (!check_type (ctx, op, ITEM_LIST)
+ || !check_type (ctx, list, ITEM_LIST))
+ {
+ item_free (null);
+ goto fail;
+ }
+
+ push (ctx, null);
+ for (struct item *iter = get_list (list); iter; iter = iter->next)
+ if (!push (ctx, new_clone (iter))
+ || !execute (ctx, get_list (op)))
+ goto fail;
+ success = true;
+
+fail:
+ item_free (op);
+ item_free (list);
+ return success;
+}
+
+defn (fn_each)
+{
+ check_stack (2);
+ struct item *op = pop (ctx);
+ struct item *list = pop (ctx);
+ bool success = false;
+ if (!check_type (ctx, op, ITEM_LIST)
+ || !check_type (ctx, list, ITEM_LIST))
+ goto fail;
+
+ for (struct item *iter = get_list (list); iter; iter = iter->next)
+ if (!push (ctx, new_clone (iter))
+ || !execute (ctx, get_list (op)))
+ goto fail;
+ success = true;
+
+fail:
+ item_free (op);
+ item_free (list);
+ return success;
+}
+
+// - - Arithmetic - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+// XXX: why not a `struct item_string *` argument?
+static bool
+push_repeated_string (struct context *ctx, struct item *op1, struct item *op2)
+{
+ struct item_string *string = (struct item_string *) op1;
+ struct item_integer *repeat = (struct item_integer *) op2;
+ assert (string->type == ITEM_STRING);
+ assert (repeat->type == ITEM_INTEGER);
+
+ if (repeat->value < 0)
+ return set_error (ctx, "cannot multiply a string by a negative value");
+
+ char *buf = NULL;
+ size_t len = string->len * repeat->value;
+ if (len < string->len && repeat->value != 0)
+ goto allocation_fail;
+
+ buf = malloc (len);
+ if (!buf)
+ goto allocation_fail;
+
+ for (size_t i = 0; i < len; i += string->len)
+ memcpy (buf + i, string->value, string->len);
+ struct item *item = new_string (buf, len);
+ free (buf);
+ return push (ctx, item);
+
+allocation_fail:
+ ctx->memory_failure = true;
+ return false;
+}
+
+defn (fn_times)
+{
+ check_stack (2);
+ struct item *op2 = pop (ctx);
+ struct item *op1 = pop (ctx);
+
+ bool ok;
+ if (op1->type == ITEM_INTEGER && op2->type == ITEM_INTEGER)
+ ok = push (ctx, new_integer (get_integer (op1) * get_integer (op2)));
+ else if (op1->type == ITEM_INTEGER && op2->type == ITEM_FLOAT)
+ ok = push (ctx, new_float (get_integer (op1) * get_float (op2)));
+ else if (op1->type == ITEM_FLOAT && op2->type == ITEM_FLOAT)
+ ok = push (ctx, new_float (get_float (op1) * get_float (op2)));
+ else if (op1->type == ITEM_FLOAT && op2->type == ITEM_INTEGER)
+ ok = push (ctx, new_float (get_float (op1) * get_integer (op2)));
+ else if (op1->type == ITEM_INTEGER && op2->type == ITEM_STRING)
+ ok = push_repeated_string (ctx, op2, op1);
+ else if (op1->type == ITEM_STRING && op2->type == ITEM_INTEGER)
+ ok = push_repeated_string (ctx, op1, op2);
+ else
+ ok = set_error (ctx, "cannot multiply `%s' and `%s'",
+ item_type_to_str (op1->type), item_type_to_str (op2->type));
+
+ item_free (op1);
+ item_free (op2);
+ return ok;
+}
+
+defn (fn_pow)
+{
+ check_stack (2);
+ struct item *op2 = pop (ctx);
+ struct item *op1 = pop (ctx);
+
+ bool ok;
+ if (op1->type == ITEM_INTEGER && op2->type == ITEM_INTEGER)
+ // TODO: implement this properly, outputting an integer
+ ok = push (ctx, new_float (powl (get_integer (op1), get_integer (op2))));
+ else if (op1->type == ITEM_INTEGER && op2->type == ITEM_FLOAT)
+ ok = push (ctx, new_float (powl (get_integer (op1), get_float (op2))));
+ else if (op1->type == ITEM_FLOAT && op2->type == ITEM_FLOAT)
+ ok = push (ctx, new_float (powl (get_float (op1), get_float (op2))));
+ else if (op1->type == ITEM_FLOAT && op2->type == ITEM_INTEGER)
+ ok = push (ctx, new_float (powl (get_float (op1), get_integer (op2))));
+ else
+ ok = set_error (ctx, "cannot exponentiate `%s' and `%s'",
+ item_type_to_str (op1->type), item_type_to_str (op2->type));
+
+ item_free (op1);
+ item_free (op2);
+ return ok;
+}
+
+defn (fn_div)
+{
+ check_stack (2);
+ struct item *op2 = pop (ctx);
+ struct item *op1 = pop (ctx);
+
+ bool ok;
+ if (op1->type == ITEM_INTEGER && op2->type == ITEM_INTEGER)
+ {
+ if (get_integer (op2) == 0)
+ ok = set_error (ctx, "division by zero");
+ else
+ ok = push (ctx, new_integer (get_integer (op1) / get_integer (op2)));
+ }
+ else if (op1->type == ITEM_INTEGER && op2->type == ITEM_FLOAT)
+ ok = push (ctx, new_float (get_integer (op1) / get_float (op2)));
+ else if (op1->type == ITEM_FLOAT && op2->type == ITEM_FLOAT)
+ ok = push (ctx, new_float (get_float (op1) / get_float (op2)));
+ else if (op1->type == ITEM_FLOAT && op2->type == ITEM_INTEGER)
+ ok = push (ctx, new_float (get_float (op1) / get_integer (op2)));
+ else
+ ok = set_error (ctx, "cannot divide `%s' and `%s'",
+ item_type_to_str (op1->type), item_type_to_str (op2->type));
+
+ item_free (op1);
+ item_free (op2);
+ return ok;
+}
+
+defn (fn_mod)
+{
+ check_stack (2);
+ struct item *op2 = pop (ctx);
+ struct item *op1 = pop (ctx);
+
+ bool ok;
+ if (op1->type == ITEM_INTEGER && op2->type == ITEM_INTEGER)
+ {
+ if (get_integer (op2) == 0)
+ ok = set_error (ctx, "division by zero");
+ else
+ ok = push (ctx, new_integer (get_integer (op1) % get_integer (op2)));
+ }
+ else if (op1->type == ITEM_INTEGER && op2->type == ITEM_FLOAT)
+ ok = push (ctx, new_float (fmodl (get_integer (op1), get_float (op2))));
+ else if (op1->type == ITEM_FLOAT && op2->type == ITEM_FLOAT)
+ ok = push (ctx, new_float (fmodl (get_float (op1), get_float (op2))));
+ else if (op1->type == ITEM_FLOAT && op2->type == ITEM_INTEGER)
+ ok = push (ctx, new_float (fmodl (get_float (op1), get_integer (op2))));
+ else
+ ok = set_error (ctx, "cannot divide `%s' and `%s'",
+ item_type_to_str (op1->type), item_type_to_str (op2->type));
+
+ item_free (op1);
+ item_free (op2);
+ return ok;
+}
+
+static bool
+push_concatenated_string (struct context *ctx,
+ struct item *op1, struct item *op2)
+{
+ struct item_string *s1 = (struct item_string *) op1;
+ struct item_string *s2 = (struct item_string *) op2;
+ assert (s1->type == ITEM_STRING);
+ assert (s2->type == ITEM_STRING);
+
+ char *buf = NULL;
+ size_t len = s1->len + s2->len;
+ if (len < s1->len || len < s2->len)
+ goto allocation_fail;
+
+ buf = malloc (len);
+ if (!buf)
+ goto allocation_fail;
+
+ memcpy (buf, s1->value, s1->len);
+ memcpy (buf + s1->len, s2->value, s2->len);
+ struct item *item = new_string (buf, len);
+ free (buf);
+ return push (ctx, item);
+
+allocation_fail:
+ ctx->memory_failure = true;
+ return false;
+
+}
+
+defn (fn_plus)
+{
+ check_stack (2);
+ struct item *op2 = pop (ctx);
+ struct item *op1 = pop (ctx);
+
+ bool ok;
+ if (op1->type == ITEM_INTEGER && op2->type == ITEM_INTEGER)
+ ok = push (ctx, new_integer (get_integer (op1) + get_integer (op2)));
+ else if (op1->type == ITEM_INTEGER && op2->type == ITEM_FLOAT)
+ ok = push (ctx, new_float (get_integer (op1) + get_float (op2)));
+ else if (op1->type == ITEM_FLOAT && op2->type == ITEM_FLOAT)
+ ok = push (ctx, new_float (get_float (op1) + get_float (op2)));
+ else if (op1->type == ITEM_FLOAT && op2->type == ITEM_INTEGER)
+ ok = push (ctx, new_float (get_float (op1) + get_integer (op2)));
+ else if (op1->type == ITEM_STRING && op2->type == ITEM_STRING)
+ ok = push_concatenated_string (ctx, op1, op2);
+ else
+ ok = set_error (ctx, "cannot add `%s' and `%s'",
+ item_type_to_str (op1->type), item_type_to_str (op2->type));
+
+ item_free (op1);
+ item_free (op2);
+ return ok;
+}
+
+defn (fn_minus)
+{
+ check_stack (2);
+ struct item *op2 = pop (ctx);
+ struct item *op1 = pop (ctx);
+
+ bool ok;
+ if (op1->type == ITEM_INTEGER && op2->type == ITEM_INTEGER)
+ ok = push (ctx, new_integer (get_integer (op1) - get_integer (op2)));
+ else if (op1->type == ITEM_INTEGER && op2->type == ITEM_FLOAT)
+ ok = push (ctx, new_float (get_integer (op1) - get_float (op2)));
+ else if (op1->type == ITEM_FLOAT && op2->type == ITEM_FLOAT)
+ ok = push (ctx, new_float (get_float (op1) - get_float (op2)));
+ else if (op1->type == ITEM_FLOAT && op2->type == ITEM_INTEGER)
+ ok = push (ctx, new_float (get_float (op1) - get_integer (op2)));
+ else
+ ok = set_error (ctx, "cannot subtract `%s' and `%s'",
+ item_type_to_str (op1->type), item_type_to_str (op2->type));
+
+ item_free (op1);
+ item_free (op2);
+ return ok;
+}
+
+// - - Comparison - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+static int
+compare_strings (struct item_string *s1, struct item_string *s2)
+{
+ // XXX: not entirely correct wrt. null bytes
+ size_t len = (s1->len < s2->len ? s1->len : s2->len) + 1;
+ return memcmp (s1->value, s2->value, len);
+}
+
+static bool compare_lists (struct item *, struct item *);
+
+static bool
+compare_list_items (struct item *op1, struct item *op2)
+{
+ if (op1->type != op2->type)
+ return false;
+
+ switch (op1->type)
+ {
+ case ITEM_STRING:
+ case ITEM_WORD:
+ return !compare_strings ((struct item_string *) op1,
+ (struct item_string *) op2);
+ case ITEM_FLOAT:
+ return get_float (op1) == get_float (op2);
+ case ITEM_INTEGER:
+ return get_integer (op1) == get_integer (op2);
+ case ITEM_LIST:
+ return compare_lists (get_list (op1), get_list (op2));
+ }
+ abort ();
+}
+
+static bool
+compare_lists (struct item *op1, struct item *op2)
+{
+ while (op1 && op2)
+ {
+ if (!compare_list_items (op1, op2))
+ return false;
+
+ op1 = op1->next;
+ op2 = op2->next;
+ }
+ return !op1 && !op2;
+}
+
+defn (fn_eq)
+{
+ check_stack (2);
+ struct item *op2 = pop (ctx);
+ struct item *op1 = pop (ctx);
+
+ bool ok;
+ if (op1->type == ITEM_INTEGER && op2->type == ITEM_INTEGER)
+ ok = push (ctx, new_integer (get_integer (op1) == get_integer (op2)));
+ else if (op1->type == ITEM_INTEGER && op2->type == ITEM_FLOAT)
+ ok = push (ctx, new_integer (get_integer (op1) == get_float (op2)));
+ else if (op1->type == ITEM_FLOAT && op2->type == ITEM_FLOAT)
+ ok = push (ctx, new_integer (get_float (op1) == get_float (op2)));
+ else if (op1->type == ITEM_FLOAT && op2->type == ITEM_INTEGER)
+ ok = push (ctx, new_integer (get_float (op1) == get_integer (op2)));
+ else if (op1->type == ITEM_LIST && op2->type == ITEM_LIST)
+ ok = push (ctx, new_integer (compare_lists
+ (get_list (op1), get_list (op2))));
+ else if (op1->type == ITEM_STRING && op2->type == ITEM_STRING)
+ ok = push (ctx, new_integer (compare_strings
+ ((struct item_string *)(op1), (struct item_string *)(op2)) == 0));
+ else
+ ok = set_error (ctx, "cannot compare `%s' and `%s'",
+ item_type_to_str (op1->type), item_type_to_str (op2->type));
+
+ item_free (op1);
+ item_free (op2);
+ return ok;
+}
+
+defn (fn_lt)
+{
+ check_stack (2);
+ struct item *op2 = pop (ctx);
+ struct item *op1 = pop (ctx);
+
+ bool ok;
+ if (op1->type == ITEM_INTEGER && op2->type == ITEM_INTEGER)
+ ok = push (ctx, new_integer (get_integer (op1) < get_integer (op2)));
+ else if (op1->type == ITEM_INTEGER && op2->type == ITEM_FLOAT)
+ ok = push (ctx, new_integer (get_integer (op1) < get_float (op2)));
+ else if (op1->type == ITEM_FLOAT && op2->type == ITEM_FLOAT)
+ ok = push (ctx, new_integer (get_float (op1) < get_float (op2)));
+ else if (op1->type == ITEM_FLOAT && op2->type == ITEM_INTEGER)
+ ok = push (ctx, new_integer (get_float (op1) < get_integer (op2)));
+ else if (op1->type == ITEM_STRING && op2->type == ITEM_STRING)
+ ok = push (ctx, new_integer (compare_strings
+ ((struct item_string *)(op1), (struct item_string *)(op2)) < 0));
+ else
+ ok = set_error (ctx, "cannot compare `%s' and `%s'",
+ item_type_to_str (op1->type), item_type_to_str (op2->type));
+
+ item_free (op1);
+ item_free (op2);
+ return ok;
+}
+
+// - - Utilities - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+defn (fn_rand)
+{
+ return push (ctx, new_float ((long double) rand ()
+ / ((long double) RAND_MAX + 1)));
+}
+
+defn (fn_time)
+{
+ return push (ctx, new_integer (time (NULL)));
+}
+
+// XXX: this is a bit too constrained; combines strftime() with gmtime()
+defn (fn_strftime)
+{
+ check_stack (2);
+ struct item *format = pop (ctx);
+ struct item *time_ = pop (ctx);
+ bool success = false;
+ if (!check_type (ctx, time_, ITEM_INTEGER)
+ || !check_type (ctx, format, ITEM_STRING))
+ goto fail;
+
+ if (get_integer (time_) < 0)
+ {
+ set_error (ctx, "invalid time value");
+ goto fail;
+ }
+
+ char buf[128];
+ time_t time__ = get_integer (time_);
+ struct tm tm;
+ gmtime_r (&time__, &tm);
+ buf[strftime (buf, sizeof buf, get_string (format), &tm)] = '\0';
+ success = push (ctx, new_string (buf, -1));
+
+fail:
+ item_free (time_);
+ item_free (format);
+ return success;
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+static void item_list_to_str (const struct item *, struct buffer *);
+
+static void
+string_to_str (const struct item_string *string, struct buffer *buf)
+{
+ buffer_append_c (buf, '"');
+ for (size_t i = 0; i < string->len; i++)
+ {
+ char c = string->value[i];
+ if (c == '\n') buffer_append (buf, "\\n", 2);
+ else if (c == '\r') buffer_append (buf, "\\r", 2);
+ else if (c == '\t') buffer_append (buf, "\\t", 2);
+ else if (!isprint (c))
+ {
+ char tmp[8];
+ snprintf (tmp, sizeof tmp, "\\x%02x", (unsigned char) c);
+ buffer_append (buf, tmp, strlen (tmp));
+ }
+ else if (c == '\\') buffer_append (buf, "\\\\", 2);
+ else if (c == '"') buffer_append (buf, "\\\"", 2);
+ else buffer_append_c (buf, c);
+ }
+ buffer_append_c (buf, '"');
+}
+
+static void
+item_to_str (const struct item *item, struct buffer *buf)
+{
+ switch (item->type)
+ {
+ char *x;
+ case ITEM_STRING:
+ string_to_str ((struct item_string *) item, buf);
+ break;
+ case ITEM_WORD:
+ {
+ struct item_word *word = (struct item_word *) item;
+ buffer_append (buf, word->value, word->len);
+ break;
+ }
+ case ITEM_INTEGER:
+ if (!(x = strdup_printf ("%lld", get_integer (item))))
+ goto alloc_failure;
+ buffer_append (buf, x, strlen (x));
+ free (x);
+ break;
+ case ITEM_FLOAT:
+ if (!(x = strdup_printf ("%Lf", get_float (item))))
+ goto alloc_failure;
+ buffer_append (buf, x, strlen (x));
+ free (x);
+ break;
+ case ITEM_LIST:
+ buffer_append_c (buf, '[');
+ item_list_to_str (get_list (item), buf);
+ buffer_append_c (buf, ']');
+ break;
+ }
+ return;
+
+alloc_failure:
+ // This is a bit hackish but it simplifies stuff
+ buf->memory_failure = true;
+ free (buf->s);
+ buf->s = NULL;
+}
+
+static void
+item_list_to_str (const struct item *script, struct buffer *buf)
+{
+ if (!script)
+ return;
+
+ item_to_str (script, buf);
+ while ((script = script->next))
+ {
+ buffer_append_c (buf, ' ');
+ item_to_str (script, buf);
+ }
+}
+
+// --- IRC protocol ------------------------------------------------------------
+
+struct message
+{
+ char *prefix; ///< Message prefix
+ char *command; ///< IRC command
+ char *params[16]; ///< Command parameters (0-terminated)
+ size_t n_params; ///< Number of parameters present
+};
+
+inline static char *
+cut_word (char **s)
+{
+ char *start = *s, *end = *s + strcspn (*s, " ");
+ *s = end + strspn (end, " ");
+ *end = '\0';
+ return start;
+}
+
+static bool
+parse_message (char *s, struct message *msg)
+{
+ memset (msg, 0, sizeof *msg);
+
+ // Ignore IRC 3.2 message tags, if present
+ if (*s == '@')
+ {
+ s += strcspn (s, " ");
+ s += strspn (s, " ");
+ }
+
+ // Prefix
+ if (*s == ':')
+ msg->prefix = cut_word (&s) + 1;
+
+ // Command
+ if (!*(msg->command = cut_word (&s)))
+ return false;
+
+ // Parameters
+ while (*s)
+ {
+ size_t n = msg->n_params++;
+ if (msg->n_params >= N_ELEMENTS (msg->params))
+ return false;
+ if (*s == ':')
+ {
+ msg->params[n] = ++s;
+ break;
+ }
+ msg->params[n] = cut_word (&s);
+ }
+ return true;
+}
+
+static struct message *
+read_message (void)
+{
+ static bool discard = false;
+ static char buf[1025];
+ static struct message msg;
+
+ bool discard_this;
+ do
+ {
+ if (!fgets (buf, sizeof buf, stdin))
+ return NULL;
+ size_t len = strlen (buf);
+
+ // Just to be on the safe side, if the line overflows our buffer,
+ // ignore everything up until the next line.
+ discard_this = discard;
+ if (len >= 2 && !strcmp (buf + len - 2, "\r\n"))
+ {
+ buf[len -= 2] = '\0';
+ discard = false;
+ }
+ else
+ discard = true;
+ }
+ // Invalid messages are silently ignored
+ while (discard_this || !parse_message (buf, &msg));
+ return &msg;
+}
+
+// --- Interfacing with the bot ------------------------------------------------
+
+#define BOT_PRINT "XB print :script: "
+
+static const char *
+get_config (const char *key)
+{
+ printf ("XB get_config :%s\r\n", key);
+ struct message *msg = read_message ();
+ if (!msg || msg->n_params <= 0)
+ exit (EXIT_FAILURE);
+ return msg->params[0];
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+// TODO: implement more functions; try to avoid writing them in C
+
+static bool
+init_runtime_library_scripts (void)
+{
+ bool ok = true;
+
+ // It's much cheaper (and more fun) to define functions in terms of other
+ // ones. The "unit tests" serve a secondary purpose of showing the usage.
+ struct script
+ {
+ const char *name; ///< Name of the function
+ const char *definition; ///< The defining script
+ const char *unit_test; ///< Trivial unit test, must return 1
+ }
+ scripts[] =
+ {
+ { "nip", "swap drop", "1 2 nip 2 =" },
+ { "over", "[dup] dip swap", "1 2 over nip nip 1 =" },
+ { "swons", "swap cons", "[2] 1 swons [1 2] =" },
+ { "first", "uncons drop", "[1 2 3] first 1 =" },
+ { "rest", "uncons swap drop", "[1 2 3] rest [2 3] =" },
+ { "reverse", "[] swap [swap cons] each", "[1 2] reverse [2 1] =" },
+ { "curry", "cons", "1 2 [+] curry call 3 =" },
+
+ { "xor", "not swap not + 1 =", "1 1 xor 0 =" },
+ { "min", "over over < [drop] [nip] if", "1 2 min 1 =" },
+ { "max", "over over > [drop] [nip] if", "1 2 max 2 =" },
+
+ { "all?", "[and] cat 1 swap fold", "[3 4 5] [> 3] all? 0 =" },
+ { "any?", "[or] cat 0 swap fold", "[3 4 5] [> 3] any? 1 =" },
+
+ { ">", "swap <", "1 2 > 0 =" },
+ { "!=", "= not", "1 2 != 1 =" },
+ { "<=", "> not", "1 2 <= 1 =" },
+ { ">=", "< not", "1 2 >= 0 =" },
+
+ // XXX: this is a bit crazy and does not work with an empty list
+ { "join", "[uncons] dip swap [[dup] dip swap [+ +] dip] each drop",
+ "[1 2 3] [>string] map \" -> \" join \"1 -> 2 -> 3\" =" },
+ };
+
+ for (size_t i = 0; i < N_ELEMENTS (scripts); i++)
+ {
+ const char *error = NULL;
+ struct item *script = parse (scripts[i].definition, &error);
+ if (error)
+ {
+ printf (BOT_PRINT "error parsing internal script `%s': %s\r\n",
+ scripts[i].definition, error);
+ ok = false;
+ }
+ else
+ ok &= register_script (scripts[i].name, script);
+ }
+
+ struct context ctx;
+ for (size_t i = 0; i < N_ELEMENTS (scripts); i++)
+ {
+ const char *error = NULL;
+ struct item *script = parse (scripts[i].unit_test, &error);
+ if (error)
+ {
+ printf (BOT_PRINT "error parsing unit test for `%s': %s\r\n",
+ scripts[i].name, error);
+ ok = false;
+ continue;
+ }
+ context_init (&ctx);
+ execute (&ctx, script);
+ item_free_list (script);
+
+ const char *failure = NULL;
+ if (ctx.memory_failure)
+ failure = "memory allocation failure";
+ else if (ctx.error)
+ failure = ctx.error;
+ else if (ctx.stack_size != 1)
+ failure = "too many results on the stack";
+ else if (ctx.stack->type != ITEM_INTEGER)
+ failure = "result is not an integer";
+ else if (get_integer (ctx.stack) != 1)
+ failure = "wrong test result";
+ if (failure)
+ {
+ printf (BOT_PRINT "error executing unit test for `%s': %s\r\n",
+ scripts[i].name, failure);
+ ok = false;
+ }
+ context_free (&ctx);
+ }
+ return ok;
+}
+
+static bool
+init_runtime_library (void)
+{
+ bool ok = true;
+
+ // Type detection
+ ok &= register_handler ("string?", fn_is_string);
+ ok &= register_handler ("word?", fn_is_word);
+ ok &= register_handler ("integer?", fn_is_integer);
+ ok &= register_handler ("float?", fn_is_float);
+ ok &= register_handler ("list?", fn_is_list);
+
+ // Type conversion
+ ok &= register_handler (">string", fn_to_string);
+ ok &= register_handler (">integer", fn_to_integer);
+ ok &= register_handler (">float", fn_to_float);
+
+ // Miscellaneous
+ ok &= register_handler ("length", fn_length);
+
+ // Basic stack manipulation
+ ok &= register_handler ("dup", fn_dup);
+ ok &= register_handler ("drop", fn_drop);
+ ok &= register_handler ("swap", fn_swap);
+
+ // Calling stuff
+ ok &= register_handler ("call", fn_call);
+ ok &= register_handler ("dip", fn_dip);
+
+ // Control flow
+ ok &= register_handler ("if", fn_if);
+ ok &= register_handler ("try", fn_try);
+
+ // List processing
+ ok &= register_handler ("map", fn_map);
+ ok &= register_handler ("filter", fn_filter);
+ ok &= register_handler ("fold", fn_fold);
+ ok &= register_handler ("each", fn_each);
+
+ // List manipulation
+ ok &= register_handler ("unit", fn_unit);
+ ok &= register_handler ("cons", fn_cons);
+ ok &= register_handler ("cat", fn_cat);
+ ok &= register_handler ("uncons", fn_uncons);
+
+ // Arithmetic operations
+ ok &= register_handler ("+", fn_plus);
+ ok &= register_handler ("-", fn_minus);
+ ok &= register_handler ("*", fn_times);
+ ok &= register_handler ("^", fn_pow);
+ ok &= register_handler ("/", fn_div);
+ ok &= register_handler ("%", fn_mod);
+
+ // Comparison
+ ok &= register_handler ("=", fn_eq);
+ ok &= register_handler ("<", fn_lt);
+
+ // Logical operations
+ ok &= register_handler ("not", fn_not);
+ ok &= register_handler ("and", fn_and);
+ ok &= register_handler ("or", fn_or);
+
+ // Utilities
+ ok &= register_handler ("rand", fn_rand);
+ ok &= register_handler ("time", fn_time);
+ ok &= register_handler ("strftime", fn_strftime);
+
+ ok &= init_runtime_library_scripts ();
+ return ok;
+}
+
+static void
+free_runtime_library (void)
+{
+ struct fn *next, *iter;
+ for (iter = g_functions; iter; iter = next)
+ {
+ next = iter->next;
+ free_function (iter);
+ }
+}
+
+// --- Function database -------------------------------------------------------
+
+// TODO: a global variable storing the various procedures (db)
+// XXX: defining procedures would ideally need some kind of an ACL
+
+static void
+read_db (void)
+{
+ // TODO
+}
+
+static void
+write_db (void)
+{
+ // TODO
+}
+
+// --- Main --------------------------------------------------------------------
+
+static char *g_prefix;
+
+struct user_info
+{
+ char *ctx; ///< Context: channel or user
+ char *ctx_quote; ///< Reply quotation
+};
+
+defn (fn_dot)
+{
+ check_stack (1);
+ struct item *item = pop (ctx);
+ struct user_info *info = ctx->user_data;
+
+ struct buffer buf = BUFFER_INITIALIZER;
+ item_to_str (item, &buf);
+ item_free (item);
+ buffer_append_c (&buf, '\0');
+ if (buf.memory_failure)
+ {
+ ctx->memory_failure = true;
+ return false;
+ }
+
+ if (buf.len > 255)
+ buf.s[255] = '\0';
+
+ printf ("PRIVMSG %s :%s%s\r\n", info->ctx, info->ctx_quote, buf.s);
+ free (buf.s);
+ return true;
+}
+
+static void
+process_message (struct message *msg)
+{
+ if (!msg->prefix
+ || strcasecmp (msg->command, "PRIVMSG")
+ || msg->n_params < 2)
+ return;
+ char *line = msg->params[1];
+
+ // Filter out only our commands
+ size_t prefix_len = strlen (g_prefix);
+ if (strncmp (line, g_prefix, prefix_len))
+ return;
+ line += prefix_len;
+
+ char *command = cut_word (&line);
+ if (strcasecmp (command, "script"))
+ return;
+
+ // Retrieve information on how to respond back
+ char *msg_ctx = msg->prefix, *x;
+ if ((x = strchr (msg_ctx, '!')))
+ *x = '\0';
+
+ char *msg_ctx_quote;
+ if (strchr ("#+&!", *msg->params[0]))
+ {
+ msg_ctx_quote = strdup_printf ("%s: ", msg_ctx);
+ msg_ctx = msg->params[0];
+ }
+ else
+ msg_ctx_quote = strdup ("");
+
+ if (!msg_ctx_quote)
+ {
+ printf (BOT_PRINT "%s\r\n", "memory allocation failure");
+ return;
+ }
+
+ struct user_info info;
+ info.ctx = msg_ctx;
+ info.ctx_quote = msg_ctx_quote;
+
+ // Finally parse and execute the macro
+ const char *error = NULL;
+ struct item *script = parse (line, &error);
+ if (error)
+ {
+ printf ("PRIVMSG %s :%s%s: %s\r\n",
+ msg_ctx, msg_ctx_quote, "parse error", error);
+ goto end;
+ }
+
+ struct context ctx;
+ context_init (&ctx);
+ ctx.user_data = &info;
+ execute (&ctx, script);
+ item_free_list (script);
+
+ const char *failure = NULL;
+ if (ctx.memory_failure)
+ failure = "memory allocation failure";
+ else if (ctx.error)
+ failure = ctx.error;
+ if (failure)
+ printf ("PRIVMSG %s :%s%s: %s\r\n",
+ msg_ctx, msg_ctx_quote, "runtime error", failure);
+ context_free (&ctx);
+end:
+ free (msg_ctx_quote);
+}
+
+int
+main (int argc, char *argv[])
+{
+ freopen (NULL, "rb", stdin); setvbuf (stdin, NULL, _IOLBF, BUFSIZ);
+ freopen (NULL, "wb", stdout); setvbuf (stdout, NULL, _IOLBF, BUFSIZ);
+
+ struct rlimit limit =
+ {
+ .rlim_cur = ADDRESS_SPACE_LIMIT,
+ .rlim_max = ADDRESS_SPACE_LIMIT
+ };
+
+ // Lower the memory limits to something sensible to prevent abuse
+ (void) setrlimit (RLIMIT_AS, &limit);
+
+ read_db ();
+ if (!init_runtime_library ()
+ || !register_handler (".", fn_dot))
+ printf (BOT_PRINT "%s\r\n", "runtime library initialization failed");
+
+ g_prefix = strdup (get_config ("prefix"));
+ printf ("XB register\r\n");
+ struct message *msg;
+ while ((msg = read_message ()))
+ process_message (msg);
+
+ free_runtime_library ();
+ free (g_prefix);
+ return 0;
+}
+
generated by cgit v1.2.3-70-g09d2 (git 2.47.0) at 2024-11-22 06:26:43 +0000