!TAIL(arg)
!UNQUOTE(arg)
!UPCASE(arg)
+
+The body may also include the following constructs:
+
+!IF (condition) !THEN true-expansion !ENDIF
+!IF (condition) !THEN true-expansion !ELSE false-expansion !ENDIF
@end display
The DEFINE command defines a macro that can later be called any number
reserved only for use with macros, which helps keep them from being
confused with other kinds of identifiers.
-@menu
-* Macro Basics::
-* Macro Arguments::
-* Controlling Macro Expansion::
-* Macro Functions::
-* Macro Settings::
-* Macro Notes::
-@end menu
-
@node Macro Basics
@subsection Macro Basics
@end example
@end deffn
+@node Macro Conditional Expansion
+@subsection Macro Conditional Expansion
+
+The @code{!IF} construct may be used inside a macro body to allow for
+conditional expansion. It takes the following forms:
+
+@example
+!IF (condition) !THEN true-expansion !ENDIF
+!IF (condition) !THEN true-expansion !ELSE false-expansion !ENDIF
+@end example
+
+When the @var{condition} evaluates to true, @var{true-expansion} is
+expanded. When it evaluates to false, @var{false-expansion} is
+expanded, if it is present. The unquoted value @samp{0} is considered
+false, and all other values are considered true.
+
+Within @var{condition}, macros, macro arguments, and macro functions
+are expanded. After expansion, the condition is evaluated as a macro
+expression that may use only the following operators, in descending
+order of operator precedence:
+
+@example
+()
+!EQ !NE !GT !LT !GE !LE = ~= <> > < >= <=
+!NOT ~
+!AND &
+!OR |
+@end example
+
+All of these operators yield a Boolean result, either @samp{0} for
+false or @samp{1} for true.
+
+If an operand is a quoted string, then the operator considers the
+contents of the quoted string; otherwise, it must be a single token.
+Thus, @code{1 = '1'} is true, and @code{'a b' = a b} is in error
+because the right-hand operand is two tokens.
+
+Comparisons in macro expressions are always string comparisons. This
+can be surprising when the operands are numbers: e.g.@: @code{1 < 1.0}
+and @code{10 < 2} both evaluate to @samp{1} (true).
+
+Macro expression comparisons are case sensitive, so that @code{a = A}
+evaluates to @samp{0} (false).
+
@node Macro Settings
@subsection Macro Settings
macro definitions.
MNEST (@pxref{SET MNEST}) limits the depth of expansion of macro
-calls, that is, the nesting level of macro expansion.
+calls, that is, the nesting level of macro expansion. The default is
+50. This is mainly useful to avoid infinite expansion in the case of
+a macro that calls itself.
MITERATE
#include "language/lexer/segment.h"
#include "language/lexer/scan.h"
#include "libpspp/assertion.h"
+#include "libpspp/cast.h"
#include "libpspp/i18n.h"
#include "libpspp/message.h"
#include "libpspp/str.h"
*/
struct parse_macro_function_ctx
{
- struct macro_token *input;
+ const struct macro_token *input;
size_t n_input;
int nesting_countdown;
const struct macro_set *macros;
parse_function_arg (struct parse_macro_function_ctx *ctx,
size_t i, struct string *farg)
{
- struct macro_token *tokens = ctx->input;
+ const struct macro_token *tokens = ctx->input;
const struct token *token = &tokens[i].token;
if (token->type == T_MACRO_ID)
{
int min_args, int max_args,
size_t *input_consumed)
{
- struct macro_token *tokens = ctx->input;
+ const struct macro_token *tokens = ctx->input;
size_t n_tokens = ctx->n_input;
if (!n_tokens
return true;
}
+struct expr_context
+ {
+ int nesting_countdown;
+ const struct macro_set *macros;
+ const struct macro_expander *me;
+ bool *expand;
+ };
+
+static char *macro_evaluate_or (const struct expr_context *ctx,
+ const struct macro_token **tokens,
+ const struct macro_token *end);
+
+static char *
+macro_evaluate_literal (const struct expr_context *ctx,
+ const struct macro_token **tokens,
+ const struct macro_token *end)
+{
+ const struct macro_token *p = *tokens;
+ if (p >= end)
+ return NULL;
+ if (p->token.type == T_LPAREN)
+ {
+ p++;
+ char *value = macro_evaluate_or (ctx, &p, end);
+ if (!value)
+ return NULL;
+ if (p >= end || p->token.type != T_RPAREN)
+ {
+ free (value);
+ printf ("expecting ')' in macro expression\n");
+ return NULL;
+ }
+ p++;
+ *tokens = p;
+ return value;
+ }
+
+ struct parse_macro_function_ctx fctx = {
+ .input = p,
+ .n_input = end - p,
+ .nesting_countdown = ctx->nesting_countdown,
+ .macros = ctx->macros,
+ .me = ctx->me,
+ .expand = ctx->expand,
+ };
+ struct string function_output = DS_EMPTY_INITIALIZER;
+ size_t function_consumed;
+ if (expand_macro_function (&fctx, &function_output, &function_consumed))
+ {
+ *tokens = p + function_consumed;
+ return ds_steal_cstr (&function_output);
+ }
+
+ *tokens = p + 1;
+ return ss_xstrdup (p->representation);
+}
+
+static char *
+macro_evaluate_logical (const struct expr_context *ctx,
+ const struct macro_token **tokens,
+ const struct macro_token *end)
+{
+ const struct macro_token *p = *tokens;
+ char *lhs = macro_evaluate_literal (ctx, &p, end);
+ if (!lhs)
+ return NULL;
+
+ enum token_type op = p < end ? p->token.type : T_STOP;
+ if (op != T_EQUALS && op != T_EQ && op != T_NE && op != T_LT
+ && op != T_GT && op != T_LE && op != T_GE)
+ {
+ *tokens = p;
+ return lhs;
+ }
+ p++;
+
+ char *rhs = macro_evaluate_literal (ctx, &p, end);
+ if (!rhs)
+ {
+ free (lhs);
+ return NULL;
+ }
+
+ struct string lhs_tmp, rhs_tmp;
+ int cmp = strcmp/*XXX*/ (unquote_string_in_place (lhs, &lhs_tmp),
+ unquote_string_in_place (rhs, &rhs_tmp));
+ ds_destroy (&lhs_tmp);
+ ds_destroy (&rhs_tmp);
+
+ free (lhs);
+ free (rhs);
+
+ bool b = (op == T_EQUALS || op == T_EQ ? !cmp
+ : op == T_NE ? cmp
+ : op == T_LT ? cmp < 0
+ : op == T_GT ? cmp > 0
+ : op == T_LE ? cmp <= 0
+ :/*op == T_GE*/cmp >= 0);
+
+ *tokens = p;
+ return xstrdup (b ? "1" : "0");
+}
+
+static char *
+macro_evaluate_not (const struct expr_context *ctx,
+ const struct macro_token **tokens,
+ const struct macro_token *end)
+{
+ const struct macro_token *p = *tokens;
+
+ unsigned int negations = 0;
+ while (p < end && p->token.type == T_NOT)
+ {
+ p++;
+ negations++;
+ }
+
+ char *operand = macro_evaluate_logical (ctx, &p, end);
+ if (!operand || !negations)
+ {
+ *tokens = p;
+ return operand;
+ }
+
+ bool b = strcmp (operand, "0") ^ (negations & 1);
+ free (operand);
+ *tokens = p;
+ return xstrdup (b ? "1" : "0");
+}
+
+static char *
+macro_evaluate_and (const struct expr_context *ctx,
+ const struct macro_token **tokens,
+ const struct macro_token *end)
+{
+ const struct macro_token *p = *tokens;
+ char *lhs = macro_evaluate_not (ctx, &p, end);
+ if (!lhs)
+ return NULL;
+
+ while (p < end && p->token.type == T_AND)
+ {
+ p++;
+ char *rhs = macro_evaluate_not (ctx, &p, end);
+ if (!rhs)
+ {
+ free (lhs);
+ return NULL;
+ }
+
+ bool b = strcmp (lhs, "0") && strcmp (rhs, "0");
+ free (lhs);
+ free (rhs);
+ lhs = xstrdup (b ? "1" : "0");
+ }
+ *tokens = p;
+ return lhs;
+}
+
+static char *
+macro_evaluate_or (const struct expr_context *ctx,
+ const struct macro_token **tokens,
+ const struct macro_token *end)
+{
+ const struct macro_token *p = *tokens;
+ char *lhs = macro_evaluate_and (ctx, &p, end);
+ if (!lhs)
+ return NULL;
+
+ while (p < end && p->token.type == T_OR)
+ {
+ p++;
+ char *rhs = macro_evaluate_and (ctx, &p, end);
+ if (!rhs)
+ {
+ free (lhs);
+ return NULL;
+ }
+
+ bool b = strcmp (lhs, "0") || strcmp (rhs, "0");
+ free (lhs);
+ free (rhs);
+ lhs = xstrdup (b ? "1" : "0");
+ }
+ *tokens = p;
+ return lhs;
+}
+
+static char *
+macro_evaluate_expression (const struct macro_token **tokens, size_t n_tokens,
+ int nesting_countdown, const struct macro_set *macros,
+ const struct macro_expander *me, bool *expand)
+{
+ const struct expr_context ctx = {
+ .nesting_countdown = nesting_countdown,
+ .macros = macros,
+ .me = me,
+ .expand = expand,
+ };
+ return macro_evaluate_or (&ctx, tokens, *tokens + n_tokens);
+}
+
+static const struct macro_token *
+find_ifend_clause (const struct macro_token *p, const struct macro_token *end)
+{
+ size_t nesting = 0;
+ for (; p < end; p++)
+ {
+ if (p->token.type != T_MACRO_ID)
+ continue;
+
+ if (ss_equals_case (p->token.string, ss_cstr ("!IF")))
+ nesting++;
+ else if (ss_equals_case (p->token.string, ss_cstr ("!IFEND")))
+ {
+ if (!nesting)
+ return p;
+ nesting--;
+ }
+ else if (ss_equals_case (p->token.string, ss_cstr ("!ELSE")) && !nesting)
+ return p;
+ }
+ return NULL;
+}
+
+static size_t
+macro_expand_if (const struct macro_token *tokens, size_t n_tokens,
+ int nesting_countdown, const struct macro_set *macros,
+ const struct macro_expander *me, bool *expand,
+ struct macro_tokens *exp)
+{
+ const struct macro_token *p = tokens;
+ const struct macro_token *end = tokens + n_tokens;
+
+ if (p >= end || !ss_equals_case (p->token.string, ss_cstr ("!IF")))
+ return 0;
+
+ p++;
+ char *result = macro_evaluate_expression (&p, end - p,
+ nesting_countdown, macros, me, expand);
+ if (!result)
+ return 0;
+ bool b = strcmp (result, "0");
+ free (result);
+
+ if (p >= end
+ || p->token.type != T_MACRO_ID
+ || !ss_equals_case (p->token.string, ss_cstr ("!THEN")))
+ {
+ printf ("!THEN expected\n");
+ return 0;
+ }
+
+ const struct macro_token *start_then = p + 1;
+ const struct macro_token *end_then = find_ifend_clause (start_then, end);
+ if (!end_then)
+ {
+ printf ("!ELSE or !IFEND expected\n");
+ return 0;
+ }
+
+ const struct macro_token *start_else, *end_if;
+ if (ss_equals_case (end_then->token.string, ss_cstr ("!ELSE")))
+ {
+ start_else = end_then + 1;
+ end_if = find_ifend_clause (start_else, end);
+ if (!end_if
+ || !ss_equals_case (end_if->token.string, ss_cstr ("!IFEND")))
+ {
+ printf ("!IFEND expected\n");
+ return 0;
+ }
+ }
+ else
+ {
+ start_else = NULL;
+ end_if = end_then;
+ }
+
+ const struct macro_token *start;
+ size_t n;
+ if (b)
+ {
+ start = start_then;
+ n = end_then - start_then;
+ }
+ else if (start_else)
+ {
+ start = start_else;
+ n = end_if - start_else;
+ }
+ else
+ {
+ start = NULL;
+ n = 0;
+ }
+
+ if (n)
+ {
+ struct macro_tokens mts = {
+ .mts = CONST_CAST (struct macro_token *, start),
+ .n = n,
+ };
+ macro_expand (&mts, nesting_countdown, macros, me, expand, exp);
+ }
+ return (end_if + 1) - tokens;
+}
+
static void
macro_expand (const struct macro_tokens *mts,
int nesting_countdown, const struct macro_set *macros,
i++;
continue;
}
+
+ size_t n = macro_expand_if (&mts->mts[i], mts->n - i,
+ nesting_countdown, macros, me, expand,
+ exp);
+ if (n > 0)
+ {
+ i += n - 1;
+ continue;
+ }
}
if (*expand)
continue;
}
- /* Maybe each arg should just be a string, either a quoted string or a
- non-quoted string containing tokens. */
struct parse_macro_function_ctx ctx = {
.input = &mts->mts[i],
.n_input = mts->n - i,
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