Merge remote-tracking branch 'upstream/master'

1 files changed, 1424 insertions, 0 deletions

diff --git a/jam-files/engine/compile.c b/jam-files/engine/compile.c
new file mode 100644
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--- /dev/null
+++ b/jam-files/engine/compile.c
@@ -0,0 +1,1424 @@
+/*
+ * Copyright 1993, 2000 Christopher Seiwald.
+ *
+ * This file is part of Jam - see jam.c for Copyright information.
+ */
+
+/*  This file is ALSO:
+ *  Copyright 2001-2004 David Abrahams.
+ *  Distributed under the Boost Software License, Version 1.0.
+ *  (See accompanying file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)
+ */
+
+# include "jam.h"
+
+# include "lists.h"
+# include "parse.h"
+# include "compile.h"
+# include "variable.h"
+# include "expand.h"
+# include "rules.h"
+# include "newstr.h"
+# include "make.h"
+# include "search.h"
+# include "hdrmacro.h"
+# include "hash.h"
+# include "modules.h"
+# include "strings.h"
+# include "builtins.h"
+# include "class.h"
+
+# include <assert.h>
+# include <string.h>
+# include <stdarg.h>
+
+/*
+ * compile.c - compile parsed jam statements
+ *
+ * External routines:
+ *
+ *  compile_append() - append list results of two statements
+ *  compile_eval() - evaluate if to determine which leg to compile
+ *  compile_foreach() - compile the "for x in y" statement
+ *  compile_if() - compile 'if' rule
+ *  compile_while() - compile 'while' rule
+ *  compile_include() - support for 'include' - call include() on file
+ *  compile_list() - expand and return a list
+ *  compile_local() - declare (and set) local variables
+ *  compile_null() - do nothing -- a stub for parsing
+ *  compile_on() - run rule under influence of on-target variables
+ *  compile_rule() - compile a single user defined rule
+ *  compile_rules() - compile a chain of rules
+ *  compile_set() - compile the "set variable" statement
+ *  compile_setcomp() - support for `rule` - save parse tree
+ *  compile_setexec() - support for `actions` - save execution string
+ *  compile_settings() - compile the "on =" (set variable on exec) statement
+ *  compile_switch() - compile 'switch' rule
+ *
+ * Internal routines:
+ *
+ *  debug_compile() - printf with indent to show rule expansion.
+ *  evaluate_rule() - execute a rule invocation
+ *
+ *  builtin_depends() - DEPENDS/INCLUDES rule
+ *  builtin_echo() - ECHO rule
+ *  builtin_exit() - EXIT rule
+ *  builtin_flags() - NOCARE, NOTFILE, TEMPORARY rule
+ *
+ * 02/03/94 (seiwald) - Changed trace output to read "setting" instead of
+ *          the awkward sounding "settings".
+ * 04/12/94 (seiwald) - Combined build_depends() with build_includes().
+ * 04/12/94 (seiwald) - actionlist() now just appends a single action.
+ * 04/13/94 (seiwald) - added shorthand L0 for null list pointer
+ * 05/13/94 (seiwald) - include files are now bound as targets, and thus
+ *          can make use of $(SEARCH)
+ * 06/01/94 (seiwald) - new 'actions existing' does existing sources
+ * 08/23/94 (seiwald) - Support for '+=' (append to variable)
+ * 12/20/94 (seiwald) - NOTIME renamed NOTFILE.
+ * 01/22/95 (seiwald) - Exit rule.
+ * 02/02/95 (seiwald) - Always rule; LEAVES rule.
+ * 02/14/95 (seiwald) - NoUpdate rule.
+ * 09/11/00 (seiwald) - new evaluate_rule() for headers().
+ * 09/11/00 (seiwald) - compile_xxx() now return LIST *.
+ *          New compile_append() and compile_list() in
+ *          support of building lists here, rather than
+ *          in jamgram.yy.
+ * 01/10/00 (seiwald) - built-ins split out to builtin.c.
+ */
+
+static void debug_compile( int which, char *s, FRAME* frame );
+int glob( char *s, char *c );
+/* Internal functions from builtins.c */
+void backtrace( FRAME *frame );
+void backtrace_line( FRAME *frame );
+void print_source_line( PARSE* p );
+
+struct frame * frame_before_python_call;
+
+void frame_init( FRAME* frame )
+{
+    frame->prev = 0;
+    frame->prev_user = 0;
+    lol_init(frame->args);
+    frame->module = root_module();
+    frame->rulename = "module scope";
+    frame->procedure = 0;
+}
+
+
+void frame_free( FRAME* frame )
+{
+    lol_free( frame->args );
+}
+
+
+/*
+ * compile_append() - append list results of two statements
+ *
+ *  parse->left more compile_append() by left-recursion
+ *  parse->right    single rule
+ */
+
+LIST * compile_append( PARSE * parse, FRAME * frame )
+{
+    /* Append right to left. */
+    return list_append(
+        parse_evaluate( parse->left, frame ),
+        parse_evaluate( parse->right, frame ) );
+}
+
+
+/*
+ * compile_eval() - evaluate if to determine which leg to compile
+ *
+ * Returns:
+ *  list    if expression true - compile 'then' clause
+ *  L0  if expression false - compile 'else' clause
+ */
+
+static int lcmp( LIST * t, LIST * s )
+{
+    int status = 0;
+
+    while ( !status && ( t || s ) )
+    {
+        char *st = t ? t->string : "";
+        char *ss = s ? s->string : "";
+
+        status = strcmp( st, ss );
+
+        t = t ? list_next( t ) : t;
+        s = s ? list_next( s ) : s;
+    }
+
+    return status;
+}
+
+LIST * compile_eval( PARSE * parse, FRAME * frame )
+{
+    LIST * ll;
+    LIST * lr;
+    LIST * s;
+    LIST * t;
+    int status = 0;
+
+    /* Short circuit lr eval for &&, ||, and 'in'. */
+
+    ll = parse_evaluate( parse->left, frame );
+    lr = 0;
+
+    switch ( parse->num )
+    {
+        case EXPR_AND:
+        case EXPR_IN : if ( ll ) goto eval; break;
+        case EXPR_OR : if ( !ll ) goto eval; break;
+        default: eval: lr = parse_evaluate( parse->right, frame );
+    }
+
+    /* Now eval. */
+    switch ( parse->num )
+    {
+    case EXPR_NOT: if ( !ll      ) status = 1; break;
+    case EXPR_AND: if ( ll && lr ) status = 1; break;
+    case EXPR_OR : if ( ll || lr ) status = 1; break;
+
+    case EXPR_IN:
+        /* "a in b": make sure each of ll is equal to something in lr. */
+        for ( t = ll; t; t = list_next( t ) )
+        {
+            for ( s = lr; s; s = list_next( s ) )
+            if ( !strcmp( t->string, s->string ) )
+                break;
+            if ( !s ) break;
+        }
+        /* No more ll? Success. */
+        if ( !t ) status = 1;
+        break;
+
+    case EXPR_EXISTS: if ( lcmp( ll, L0 ) != 0 ) status = 1; break;
+    case EXPR_EQUALS: if ( lcmp( ll, lr ) == 0 ) status = 1; break;
+    case EXPR_NOTEQ : if ( lcmp( ll, lr ) != 0 ) status = 1; break;
+    case EXPR_LESS  : if ( lcmp( ll, lr ) < 0  ) status = 1; break;
+    case EXPR_LESSEQ: if ( lcmp( ll, lr ) <= 0 ) status = 1; break;
+    case EXPR_MORE  : if ( lcmp( ll, lr ) > 0  ) status = 1; break;
+    case EXPR_MOREEQ: if ( lcmp( ll, lr ) >= 0 ) status = 1; break;
+    }
+
+    if ( DEBUG_IF )
+    {
+        debug_compile( 0, "if", frame );
+        list_print( ll );
+        printf( "(%d) ", status );
+        list_print( lr );
+        printf( "\n" );
+    }
+
+    /* Find something to return. */
+    /* In odd circumstances (like "" = "") */
+    /* we'll have to return a new string. */
+
+    if ( !status ) t = 0;
+    else if ( ll ) t = ll, ll = 0;
+    else if ( lr ) t = lr, lr = 0;
+    else t = list_new( L0, newstr( "1" ) );
+
+    if ( ll ) list_free( ll );
+    if ( lr ) list_free( lr );
+    return t;
+}
+
+
+/*
+ * compile_foreach() - compile the "for x in y" statement
+ *
+ * Compile_foreach() resets the given variable name to each specified
+ * value, executing the commands enclosed in braces for each iteration.
+ *
+ *  parse->string   index variable
+ *  parse->left variable values
+ *  parse->right    rule to compile
+ */
+
+LIST * compile_foreach( PARSE * parse, FRAME * frame )
+{
+    LIST     * nv = parse_evaluate( parse->left, frame );
+    LIST     * l;
+    SETTINGS * s = 0;
+
+    if ( parse->num )
+    {
+        s = addsettings( s, VAR_SET, parse->string, L0 );
+        pushsettings( s );
+    }
+
+    /* Call var_set to reset $(parse->string) for each val. */
+
+    for ( l = nv; l; l = list_next( l ) )
+    {
+        LIST * val = list_new( L0, copystr( l->string ) );
+        var_set( parse->string, val, VAR_SET );
+        list_free( parse_evaluate( parse->right, frame ) );
+    }
+
+    if ( parse->num )
+    {
+        popsettings( s );
+        freesettings( s );
+    }
+
+    list_free( nv );
+
+    return L0;
+}
+
+/*
+ * compile_if() - compile 'if' rule
+ *
+ *  parse->left     condition tree
+ *  parse->right        then tree
+ *  parse->third        else tree
+ */
+
+LIST * compile_if( PARSE * p, FRAME * frame )
+{
+    LIST * l = parse_evaluate( p->left, frame );
+    if ( l )
+    {
+        list_free( l );
+        return parse_evaluate( p->right, frame );
+    }
+    return parse_evaluate( p->third, frame );
+}
+
+
+LIST * compile_while( PARSE * p, FRAME * frame )
+{
+    LIST * r = 0;
+    LIST * l;
+    while ( ( l = parse_evaluate( p->left, frame ) ) )
+    {
+        list_free( l );
+        if ( r ) list_free( r );
+        r = parse_evaluate( p->right, frame );
+    }
+    return r;
+}
+
+
+/*
+ * compile_include() - support for 'include' - call include() on file
+ *
+ *  parse->left list of files to include (can only do 1)
+ */
+
+LIST * compile_include( PARSE * parse, FRAME * frame )
+{
+    LIST * nt = parse_evaluate( parse->left, frame );
+
+    if ( DEBUG_COMPILE )
+    {
+        debug_compile( 0, "include", frame);
+        list_print( nt );
+        printf( "\n" );
+    }
+
+    if ( nt )
+    {
+        TARGET * t = bindtarget( nt->string );
+
+        /* DWA 2001/10/22 - Perforce Jam cleared the arguments here, which
+         * prevents an included file from being treated as part of the body of a
+         * rule. I did not see any reason to do that, so I lifted the
+         * restriction.
+         */
+
+        /* Bind the include file under the influence of */
+        /* "on-target" variables.  Though they are targets, */
+        /* include files are not built with make(). */
+
+        pushsettings( t->settings );
+        /* We don't expect that file to be included is generated by some
+           action. Therefore, pass 0 as third argument.
+           If the name resolves to directory, let it error out.  */
+        t->boundname = search( t->name, &t->time, 0, 0 );
+        popsettings( t->settings );
+
+        parse_file( t->boundname, frame );
+    }
+
+    list_free( nt );
+
+    return L0;
+}
+
+static LIST* evaluate_in_module ( char* module_name, PARSE * p, FRAME* frame)
+{
+    LIST* result;
+
+    module_t* outer_module = frame->module;
+    frame->module = module_name ? bindmodule( module_name ) : root_module();
+
+    if ( outer_module != frame->module )
+    {
+        exit_module( outer_module );
+        enter_module( frame->module );
+    }
+
+    result = parse_evaluate( p, frame );
+
+    if ( outer_module != frame->module )
+    {
+        exit_module( frame->module );
+        enter_module( outer_module );
+        frame->module = outer_module;
+    }
+
+    return result;
+}
+
+
+LIST * compile_module( PARSE * p, FRAME * frame )
+{
+    /* Here we are entering a module declaration block. */
+    LIST * module_name = parse_evaluate( p->left, frame );
+    LIST * result = evaluate_in_module( module_name ? module_name->string : 0,
+                                       p->right, frame );
+    list_free( module_name );
+    return result;
+}
+
+
+LIST * compile_class( PARSE * p, FRAME * frame )
+{
+    /** Todo: check for empty class name.
+        Check for class redeclaration. */
+
+    char * class_module = 0;
+
+    LIST * name = parse_evaluate( p->left->right, frame );
+    LIST * bases = 0;
+
+    if ( p->left->left )
+        bases = parse_evaluate( p->left->left->right, frame );
+
+    class_module = make_class_module( name, bases, frame );
+    evaluate_in_module( class_module, p->right, frame );
+
+    return L0;
+}
+
+
+/*
+ * compile_list() - expand and return a list.
+ *
+ *  parse->string - character string to expand.
+ */
+
+LIST * compile_list( PARSE * parse, FRAME * frame )
+{
+    /* s is a copyable string */
+    char * s = parse->string;
+    return var_expand( L0, s, s + strlen( s ), frame->args, 1 );
+}
+
+
+/*
+ * compile_local() - declare (and set) local variables.
+ *
+ *  parse->left    list of variables
+ *  parse->right   list of values
+ *  parse->third   rules to execute
+ */
+
+LIST * compile_local( PARSE * parse, FRAME * frame )
+{
+    LIST * l;
+    SETTINGS * s = 0;
+    LIST     * nt = parse_evaluate( parse->left, frame );
+    LIST     * ns = parse_evaluate( parse->right, frame );
+    LIST     * result;
+
+    if ( DEBUG_COMPILE )
+    {
+        debug_compile( 0, "local", frame );
+        list_print( nt );
+        printf( " = " );
+        list_print( ns );
+        printf( "\n" );
+    }
+
+    /* Initial value is ns. */
+    for ( l = nt; l; l = list_next( l ) )
+        s = addsettings( s, VAR_SET, l->string, list_copy( (LIST *)0, ns ) );
+
+    list_free( ns );
+    list_free( nt );
+
+    /* Note that callees of the current context get this "local" variable,
+     * making it not so much local as layered.
+     */
+
+    pushsettings( s );
+    result = parse_evaluate( parse->third, frame );
+    popsettings( s );
+
+    freesettings( s );
+
+    return result;
+}
+
+
+/*
+ * compile_null() - do nothing -- a stub for parsing.
+ */
+
+LIST * compile_null( PARSE * parse, FRAME * frame )
+{
+    return L0;
+}
+
+
+/*
+ * compile_on() - run rule under influence of on-target variables
+ *
+ *  parse->left    list of files to include (can only do 1).
+ *  parse->right   rule to run.
+ *
+ * EXPERIMENTAL!
+ */
+
+LIST * compile_on( PARSE * parse, FRAME * frame )
+{
+    LIST * nt = parse_evaluate( parse->left, frame );
+    LIST * result = 0;
+
+    if ( DEBUG_COMPILE )
+    {
+        debug_compile( 0, "on", frame );
+        list_print( nt );
+        printf( "\n" );
+    }
+
+    if ( nt )
+    {
+        TARGET * t = bindtarget( nt->string );
+        pushsettings( t->settings );
+        result = parse_evaluate( parse->right, frame );
+        popsettings( t->settings );
+    }
+
+    list_free( nt );
+
+    return result;
+}
+
+
+/*
+ * compile_rule() - compile a single user defined rule.
+ *
+ *  parse->string   name of user defined rule.
+ *  parse->left     parameters (list of lists) to rule, recursing left.
+ *
+ * Wrapped around evaluate_rule() so that headers() can share it.
+ */
+
+LIST * compile_rule( PARSE * parse, FRAME * frame )
+{
+    FRAME   inner[ 1 ];
+    LIST  * result;
+    PARSE * p;
+
+    /* Build up the list of arg lists. */
+    frame_init( inner );
+    inner->prev = frame;
+    inner->prev_user = frame->module->user_module ? frame : frame->prev_user;
+    inner->module = frame->module;  /* This gets fixed up in evaluate_rule(), below. */
+    inner->procedure = parse;
+    /* Special-case LOL of length 1 where the first list is totally empty.
+       This is created when calling functions with no parameters, due to
+       the way jam grammar is written. This is OK when one jam function
+       calls another, but really not good when Jam function calls Python.  */
+    if ( parse->left->left == NULL && parse->left->right->func == compile_null)
+        ;
+    else
+        for ( p = parse->left; p; p = p->left )
+            lol_add( inner->args, parse_evaluate( p->right, frame ) );
+
+    /* And invoke the rule. */
+    result = evaluate_rule( parse->string, inner );
+    frame_free( inner );
+    return result;
+}
+
+
+static void argument_error( char * message, RULE * rule, FRAME * frame, LIST* arg )
+{
+    LOL * actual = frame->args;
+    assert( frame->procedure != 0 );
+    backtrace_line( frame->prev );
+    printf( "*** argument error\n* rule %s ( ", frame->rulename );
+    lol_print( rule->arguments->data );
+    printf( " )\n* called with: ( " );
+    lol_print( actual );
+    printf( " )\n* %s %s\n", message, arg ? arg->string : "" );
+    print_source_line( rule->procedure );
+    printf( "see definition of rule '%s' being called\n", rule->name );
+    backtrace( frame->prev );
+    exit( 1 );
+}
+
+
+/* Define delimiters for type check elements in argument lists (and return type
+ * specifications, eventually).
+ */
+# define TYPE_OPEN_DELIM '['
+# define TYPE_CLOSE_DELIM ']'
+
+/*
+ * is_type_name() - true iff the given string represents a type check
+ * specification.
+ */
+
+static int is_type_name( char * s )
+{
+    return ( s[ 0 ] == TYPE_OPEN_DELIM ) &&
+        ( s[ strlen( s ) - 1 ] == TYPE_CLOSE_DELIM );
+}
+
+
+/*
+ * arg_modifier - if the next element of formal is a single character, return
+ * that; return 0 otherwise. Used to extract "*+?" modifiers * from argument
+ * lists.
+ */
+
+static char arg_modifier( LIST * formal )
+{
+    if ( formal->next )
+    {
+        char * next = formal->next->string;
+        if ( next && ( next[ 0 ] != 0 ) && ( next[ 1 ] == 0 ) )
+            return next[ 0 ];
+    }
+    return 0;
+}
+
+
+/*
+ * type_check() - checks that each element of values satisfies the requirements
+ * of type_name.
+ *
+ *      caller   - the frame of the rule calling the rule whose arguments are
+ *                 being checked
+ *
+ *      called   - the rule being called
+ *
+ *      arg_name - a list element containing the name of the argument being
+ *                 checked
+ */
+
+static void type_check
+(
+    char  * type_name,
+    LIST  * values,
+    FRAME * caller,
+    RULE  * called,
+    LIST  * arg_name
+)
+{
+    static module_t * typecheck = 0;
+
+    /* If nothing to check, bail now. */
+    if ( !values || !type_name )
+        return;
+
+    if ( !typecheck )
+        typecheck = bindmodule( ".typecheck" );
+
+    /* If the checking rule can not be found, also bail. */
+    {
+        RULE checker_, *checker = &checker_;
+
+        checker->name = type_name;
+        if ( !typecheck->rules || !hashcheck( typecheck->rules, (HASHDATA * *)&checker ) )
+            return;
+    }
+
+    exit_module( caller->module );
+
+    while ( values != 0 )
+    {
+        LIST *error;
+        FRAME frame[1];
+        frame_init( frame );
+        frame->module = typecheck;
+        frame->prev = caller;
+        frame->prev_user = caller->module->user_module ? caller : caller->prev_user;
+
+        enter_module( typecheck );
+        /* Prepare the argument list */
+        lol_add( frame->args, list_new( L0, values->string ) );
+        error = evaluate_rule( type_name, frame );
+
+        exit_module( typecheck );
+
+        if ( error )
+            argument_error( error->string, called, caller, arg_name );
+
+        frame_free( frame );
+        values = values->next;
+    }
+
+    enter_module( caller->module );
+}
+
+/*
+ * collect_arguments() - local argument checking and collection
+ */
+static SETTINGS *
+collect_arguments( RULE* rule, FRAME* frame )
+{
+    SETTINGS *locals = 0;
+
+    LOL * all_actual = frame->args;
+    LOL * all_formal = rule->arguments ? rule->arguments->data : 0;
+    if ( all_formal ) /* Nothing to set; nothing to check */
+    {
+        int max = all_formal->count > all_actual->count
+            ? all_formal->count
+            : all_actual->count;
+
+        int n;
+        for ( n = 0; n < max ; ++n )
+        {
+            LIST *actual = lol_get( all_actual, n );
+            char *type_name = 0;
+
+            LIST *formal;
+            for ( formal = lol_get( all_formal, n ); formal; formal = formal->next )
+            {
+                char* name = formal->string;
+
+                if ( is_type_name(name) )
+                {
+                    if ( type_name )
+                        argument_error( "missing argument name before type name:", rule, frame, formal );
+
+                    if ( !formal->next )
+                        argument_error( "missing argument name after type name:", rule, frame, formal );
+
+                    type_name = formal->string;
+                }
+                else
+                {
+                    LIST* value = 0;
+                    char modifier;
+                    LIST* arg_name = formal; /* hold the argument name for type checking */
+                    int multiple = 0;
+
+                    /* Stop now if a variable number of arguments are specified */
+                    if ( name[0] == '*' && name[1] == 0 )
+                        return locals;
+
+                    modifier = arg_modifier( formal );
+
+                    if ( !actual && modifier != '?' && modifier != '*' )
+                        argument_error( "missing argument", rule, frame, formal );
+
+                    switch ( modifier )
+                    {
+                    case '+':
+                    case '*':
+                        value = list_copy( 0, actual );
+                        multiple = 1;
+                        actual = 0;
+                        /* skip an extra element for the modifier */
+                        formal = formal->next;
+                        break;
+                    case '?':
+                        /* skip an extra element for the modifier */
+                        formal = formal->next;
+                        /* fall through */
+                    default:
+                        if ( actual ) /* in case actual is missing */
+                        {
+                            value = list_new( 0, actual->string );
+                            actual = actual->next;
+                        }
+                    }
+
+                    locals = addsettings(locals, VAR_SET, name, value);
+                    locals->multiple = multiple;
+                    type_check( type_name, value, frame, rule, arg_name );
+                    type_name = 0;
+                }
+            }
+
+            if ( actual )
+            {
+                argument_error( "extra argument", rule, frame, actual );
+            }
+        }
+    }
+    return locals;
+}
+
+RULE *
+enter_rule( char *rulename, module_t *target_module );
+
+#ifdef HAVE_PYTHON
+
+static int python_instance_number = 0;
+
+
+/* Given a Python object, return a string to use in Jam
+   code instead of said object.
+   If the object is string, use the string value
+   If the object implemenets __jam_repr__ method, use that.
+   Otherwise return 0.
+
+   The result value is newstr-ed.  */
+char *python_to_string(PyObject* value)
+{
+    if (PyString_Check(value))
+    {
+        return newstr(PyString_AsString(value));
+    }
+    else
+    {
+        /* See if this is an instance that defines special __jam_repr__
+           method. */
+        if (PyInstance_Check(value)
+            && PyObject_HasAttrString(value, "__jam_repr__"))
+        {
+            PyObject* repr = PyObject_GetAttrString(value, "__jam_repr__");
+            if (repr)
+            {
+                PyObject* arguments2 = PyTuple_New(0);
+                PyObject* value2 = PyObject_Call(repr, arguments2, 0);
+                Py_DECREF(repr);
+                Py_DECREF(arguments2);
+                if (PyString_Check(value2))
+                {
+                    return newstr(PyString_AsString(value2));
+                }
+                Py_DECREF(value2);
+            }
+        }
+        return 0;
+    }
+}
+
+static LIST*
+call_python_function(RULE* r, FRAME* frame)
+{
+    LIST * result = 0;
+    PyObject * arguments = 0;
+    PyObject * kw = NULL;
+    int i ;
+    PyObject * py_result;
+
+    if (r->arguments)
+    {
+        SETTINGS * args;
+
+        arguments = PyTuple_New(0);
+        kw = PyDict_New();
+
+        for (args = collect_arguments(r, frame); args; args = args->next)
+        {
+            PyObject *key = PyString_FromString(args->symbol);
+            PyObject *value = 0;
+            if (args->multiple)
+                value = list_to_python(args->value);
+            else {
+                if (args->value)
+                    value = PyString_FromString(args->value->string);
+            }
+
+            if (value)
+                PyDict_SetItem(kw, key, value);
+            Py_DECREF(key);
+            Py_XDECREF(value);
+        }
+    }
+    else
+    {
+        arguments = PyTuple_New( frame->args->count );
+        for ( i = 0; i < frame->args->count; ++i )
+        {
+            PyObject * arg = PyList_New(0);
+            LIST* l = lol_get( frame->args, i);
+            
+            for ( ; l; l = l->next )
+            {
+                PyObject * v = PyString_FromString(l->string);
+                PyList_Append( arg, v );
+                Py_DECREF(v);
+            }
+            /* Steals reference to 'arg' */
+            PyTuple_SetItem( arguments, i, arg );
+        }
+    }
+
+    frame_before_python_call = frame;
+    py_result = PyObject_Call( r->python_function, arguments, kw );
+    Py_DECREF(arguments);
+    Py_XDECREF(kw);
+    if ( py_result != NULL )
+    {
+        if ( PyList_Check( py_result ) )
+        {
+            int size = PyList_Size( py_result );
+            int i;
+            for ( i = 0; i < size; ++i )
+            {
+                PyObject * item = PyList_GetItem( py_result, i );
+                char *s = python_to_string (item);
+                if (!s) {
+                    fprintf( stderr, "Non-string object returned by Python call.\n" );
+                } else {
+                    result = list_new (result, s);
+                }
+            }
+        }
+        else if ( py_result == Py_None )
+        {
+            result = L0;
+        }
+        else 
+        {
+            char *s = python_to_string(py_result);
+            if (s)
+                result = list_new(0, s);
+            else 
+                /* We have tried all we could.  Return empty list. There are
+                   cases, e.g.  feature.feature function that should return
+                   value for the benefit of Python code and which also can be
+                   called by Jam code, where no sensible value can be
+                   returned. We cannot even emit a warning, since there will
+                   be a pile of them.  */                
+                result = L0;                    
+        }
+
+        Py_DECREF( py_result );
+    }
+    else
+    {
+        PyErr_Print();
+        fprintf(stderr,"Call failed\n");
+    }
+
+    return result;
+}
+
+
+module_t * python_module()
+{
+    static module_t * python = 0;
+    if ( !python )
+        python = bindmodule("__python__");
+    return python;
+}
+
+#endif
+
+
+/*
+ * evaluate_rule() - execute a rule invocation.
+ */
+
+LIST *
+evaluate_rule(
+    char  * rulename,
+    FRAME * frame )
+{
+    LIST          * result = L0;
+    RULE          * rule;
+    profile_frame   prof[1];
+    module_t      * prev_module = frame->module;
+
+    LIST * l;
+    {
+        LOL arg_context_, * arg_context = &arg_context_;
+        if ( !frame->prev )
+            lol_init(arg_context);
+        else
+            arg_context = frame->prev->args;
+        l = var_expand( L0, rulename, rulename+strlen(rulename), arg_context, 0 );
+    }
+
+    if ( !l )
+    {
+        backtrace_line( frame->prev );
+        printf( "warning: rulename %s expands to empty string\n", rulename );
+        backtrace( frame->prev );
+        return result;
+    }
+
+    rulename = l->string;
+    rule = bindrule( l->string, frame->module );
+
+#ifdef HAVE_PYTHON
+    if ( rule->python_function )
+    {
+        /* The below messing with modules is due to the way modules are
+         * implemented in Jam. Suppose we are in module M1 now. The global
+         * variable map actually holds 'M1' variables, and M1->variables hold
+         * global variables.
+         *
+         * If we call Python right away, Python calls back Jam and then Jam
+         * does 'module M1 { }' then Jam will try to swap the current global
+         * variables with M1->variables. The result will be that global
+         * variables map will hold global variables, and any variable settings
+         * we do will go to the global module, not M1.
+         *
+         * By restoring basic state, where the global variable map holds global
+         * variable, we make sure any future 'module M1' entry will work OK.
+         */
+
+        LIST * result;
+        module_t * m = python_module();
+
+        frame->module = m;
+
+        exit_module( prev_module );
+        enter_module( m );
+
+        result = call_python_function( rule, frame );
+
+        exit_module( m );
+        enter_module ( prev_module );
+
+        return result;
+    }
+#endif
+
+    /* Drop the rule name. */
+    l = list_pop_front( l );
+
+    /* Tack the rest of the expansion onto the front of the first argument. */
+    frame->args->list[0] = list_append( l, lol_get( frame->args, 0 ) );
+
+    if ( DEBUG_COMPILE )
+    {
+        /* Try hard to indicate in which module the rule is going to execute. */
+        if ( rule->module != frame->module
+             && rule->procedure != 0 && strcmp( rulename, rule->procedure->rulename ) )
+        {
+            char buf[256] = "";
+            strncat( buf, rule->module->name, sizeof( buf ) - 1 );
+            strncat( buf, rule->name, sizeof( buf ) - 1 );
+            debug_compile( 1, buf, frame );
+        }
+        else
+        {
+            debug_compile( 1, rulename, frame );
+        }
+
+        lol_print( frame->args );
+        printf( "\n" );
+    }
+
+    if ( rule->procedure && rule->module != prev_module )
+    {
+        /* Propagate current module to nested rule invocations. */
+        frame->module = rule->module;
+
+        /* Swap variables. */
+        exit_module( prev_module );
+        enter_module( rule->module );
+    }
+
+    /* Record current rule name in frame. */
+    if ( rule->procedure )
+    {
+        frame->rulename = rulename;
+        /* And enter record profile info. */
+        if ( DEBUG_PROFILE )
+            profile_enter( rule->procedure->rulename, prof );
+    }
+
+    /* Check traditional targets $(<) and sources $(>). */
+    if ( !rule->actions && !rule->procedure )
+    {
+        backtrace_line( frame->prev );
+        printf( "rule %s unknown in module %s\n", rule->name, frame->module->name );
+        backtrace( frame->prev );
+        exit( 1 );
+    }
+
+    /* If this rule will be executed for updating the targets then construct the
+     * action for make().
+     */
+    if ( rule->actions )
+    {
+        TARGETS * t;
+        ACTION  * action;
+
+        /* The action is associated with this instance of this rule. */
+        action = (ACTION *)BJAM_MALLOC( sizeof( ACTION ) );
+        memset( (char *)action, '\0', sizeof( *action ) );
+
+        action->rule = rule;
+        action->targets = targetlist( (TARGETS *)0, lol_get( frame->args, 0 ) );
+        action->sources = targetlist( (TARGETS *)0, lol_get( frame->args, 1 ) );
+
+        /* If we have a group of targets all being built using the same action
+         * then we must not allow any of them to be used as sources unless they
+         * had all already been built in the first place or their joined action
+         * has had a chance to finish its work and build all of them anew.
+         *
+         * Without this it might be possible, in case of a multi-process build,
+         * for their action, triggered by buiding one of the targets, to still
+         * be running when another target in the group reports as done in order
+         * to avoid triggering the same action again and gets used prematurely.
+         *
+         * As a quick-fix to achieve this effect we make all the targets list
+         * each other as 'included targets'. More precisely, we mark the first
+         * listed target as including all the other targets in the list and vice
+         * versa. This makes anyone depending on any of those targets implicitly
+         * depend on all of them, thus making sure none of those targets can be
+         * used as sources until all of them have been built. Note that direct
+         * dependencies could not have been used due to the 'circular
+         * dependency' issue.
+         *
+         * TODO: Although the current implementation solves the problem of one
+         * of the targets getting used before its action completes its work it
+         * also forces the action to run whenever any of the targets in the
+         * group is not up to date even though some of them might not actually
+         * be used by the targets being built. We should see how we can
+         * correctly recognize such cases and use that to avoid running the
+         * action if possible and not rebuild targets not actually depending on
+         * targets that are not up to date.
+         *
+         * TODO: Using the 'include' feature might have side-effects due to
+         * interaction with the actual 'inclusion scanning' system. This should
+         * be checked.
+         */
+        if ( action->targets )
+        {
+            TARGET * t0 = action->targets->target;
+            for ( t = action->targets->next; t; t = t->next )
+            {
+                target_include( t->target, t0 );
+                target_include( t0, t->target );
+            }
+        }
+
+        /* Append this action to the actions of each target. */
+        for ( t = action->targets; t; t = t->next )
+            t->target->actions = actionlist( t->target->actions, action );
+    }
+
+    /* Now recursively compile any parse tree associated with this rule.
+     * parse_refer()/parse_free() call pair added to ensure rule not freed
+     * during use.
+     */
+    if ( rule->procedure )
+    {
+        SETTINGS * local_args = collect_arguments( rule, frame );
+        PARSE * parse = rule->procedure;
+        parse_refer( parse );
+
+        pushsettings( local_args );
+        result = parse_evaluate( parse, frame );
+        popsettings( local_args );
+        freesettings( local_args );
+
+        parse_free( parse );
+    }
+
+    if ( frame->module != prev_module )
+    {
+        exit_module( frame->module );
+        enter_module( prev_module );
+    }
+
+    if ( DEBUG_PROFILE && rule->procedure )
+        profile_exit( prof );
+
+    if ( DEBUG_COMPILE )
+        debug_compile( -1, 0, frame);
+
+    return result;
+}
+
+
+/*
+ * Call the given rule with the specified parameters. The parameters should be
+ * of type LIST* and end with a NULL pointer. This differs from 'evaluate_rule'
+ * in that frame for the called rule is prepared inside 'call_rule'.
+ *
+ * This function is useful when a builtin rule (in C) wants to call another rule
+ * which might be implemented in Jam.
+ */
+
+LIST * call_rule( char * rulename, FRAME * caller_frame, ... )
+{
+    va_list va;
+    LIST * result;
+
+    FRAME       inner[1];
+    frame_init( inner );
+    inner->prev = caller_frame;
+    inner->prev_user = caller_frame->module->user_module ?
+        caller_frame : caller_frame->prev_user;
+    inner->module = caller_frame->module;
+    inner->procedure = 0;
+
+    va_start( va, caller_frame );
+    for ( ; ; )
+    {
+        LIST * l = va_arg( va, LIST* );
+        if ( !l )
+            break;
+        lol_add( inner->args, l );
+    }
+    va_end( va );
+
+    result = evaluate_rule( rulename, inner );
+
+    frame_free( inner );
+
+    return result;
+}
+
+
+/*
+ * compile_rules() - compile a chain of rules
+ *
+ *  parse->left single rule
+ *  parse->right    more compile_rules() by right-recursion
+ */
+
+LIST * compile_rules( PARSE * parse, FRAME * frame )
+{
+    /* Ignore result from first statement; return the 2nd. */
+    /* Optimize recursion on the right by looping. */
+    do list_free( parse_evaluate( parse->left, frame ) );
+    while ( ( parse = parse->right )->func == compile_rules );
+    return parse_evaluate( parse, frame );
+}
+
+
+/*
+ * assign_var_mode() - convert ASSIGN_XXX compilation flag into corresponding
+ *                     VAR_XXX variable set flag.
+ */
+
+static int assign_var_mode( int parsenum, char const * * tracetext )
+{
+    char const * trace;
+    int          setflag;
+    switch ( parsenum )
+    {
+        case ASSIGN_SET    : setflag = VAR_SET    ; trace = "=" ; break;
+        case ASSIGN_APPEND : setflag = VAR_APPEND ; trace = "+="; break;
+        case ASSIGN_DEFAULT: setflag = VAR_DEFAULT; trace = "?="; break;
+        default:             setflag = VAR_SET    ; trace = ""  ; break;
+    }
+    if ( tracetext )
+        *tracetext = trace ;
+    return setflag;
+}
+
+/*
+ * compile_set() - compile the "set variable" statement
+ *
+ *  parse->left variable names
+ *  parse->right    variable values
+ *  parse->num  ASSIGN_SET/APPEND/DEFAULT
+ */
+
+LIST * compile_set( PARSE * parse, FRAME * frame )
+{
+    LIST       * nt = parse_evaluate( parse->left, frame );
+    LIST       * ns = parse_evaluate( parse->right, frame );
+    LIST       * l;
+    char const * trace;
+    int          setflag = assign_var_mode( parse->num, &trace );
+
+    if ( DEBUG_COMPILE )
+    {
+        debug_compile( 0, "set", frame );
+        list_print( nt );
+        printf( " %s ", trace );
+        list_print( ns );
+        printf( "\n" );
+    }
+
+    /* Call var_set to set variable. var_set keeps ns, so need to copy it. */
+    for ( l = nt; l; l = list_next( l ) )
+        var_set( l->string, list_copy( L0, ns ), setflag );
+    list_free( nt );
+    return ns;
+}
+
+
+/*
+ * compile_setcomp() - support for `rule` - save parse tree.
+ *
+ *  parse->string  rule name
+ *  parse->left    rules for rule
+ *  parse->right   optional list-of-lists describing arguments
+ */
+
+LIST * compile_setcomp( PARSE * parse, FRAME * frame )
+{
+    argument_list * arg_list = 0;
+
+    /* Create new LOL describing argument requirements if supplied. */
+    if ( parse->right )
+    {
+        PARSE * p;
+        arg_list = args_new();
+        for ( p = parse->right; p; p = p->left )
+            lol_add( arg_list->data, parse_evaluate( p->right, frame ) );
+    }
+
+    new_rule_body( frame->module, parse->string, arg_list, parse->left, !parse->num );
+    return L0;
+}
+
+
+/*
+ * compile_setexec() - support for `actions` - save execution string.
+ *
+ *  parse->string   rule name
+ *  parse->string1  OS command string
+ *  parse->num      flags
+ *  parse->left     `bind` variables
+ *
+ * Note that the parse flags (as defined in compile.h) are transferred directly
+ * to the rule flags (as defined in rules.h).
+ */
+
+LIST * compile_setexec( PARSE * parse, FRAME * frame )
+{
+    LIST * bindlist = parse_evaluate( parse->left, frame );
+    new_rule_actions( frame->module, parse->string, parse->string1, bindlist, parse->num );
+    return L0;
+}
+
+
+/*
+ * compile_settings() - compile the "on =" (set variable on exec) statement.
+ *
+ *  parse->left   variable names
+ *  parse->right  target name
+ *  parse->third  variable value
+ *  parse->num    ASSIGN_SET/APPEND
+ */
+
+LIST * compile_settings( PARSE * parse, FRAME * frame )
+{
+    LIST       * nt = parse_evaluate( parse->left, frame );
+    LIST       * ns = parse_evaluate( parse->third, frame );
+    LIST       * targets = parse_evaluate( parse->right, frame );
+    LIST       * ts;
+    char const * trace;
+    int          setflag = assign_var_mode( parse->num, &trace );
+
+    if ( DEBUG_COMPILE )
+    {
+        debug_compile( 0, "set", frame );
+        list_print( nt );
+        printf( " on " );
+        list_print( targets );
+        printf( " %s ", trace );
+        list_print( ns );
+        printf( "\n" );
+    }
+
+    /* Call addsettings() to save variable setting. addsettings() keeps ns, so
+     * need to copy it. Pass append flag to addsettings().
+     */
+    for ( ts = targets; ts; ts = list_next( ts ) )
+    {
+        TARGET * t = bindtarget( ts->string );
+        LIST   * l;
+
+        for ( l = nt; l; l = list_next( l ) )
+        t->settings = addsettings( t->settings, setflag, l->string,
+            list_copy( (LIST *)0, ns ) );
+    }
+
+    list_free( nt );
+    list_free( targets );
+    return ns;
+}
+
+
+/*
+ * compile_switch() - compile 'switch' rule.
+ *
+ *  parse->left   switch value (only 1st used)
+ *  parse->right  cases
+ *
+ *  cases->left   1st case
+ *  cases->right  next cases
+ *
+ *  case->string  argument to match
+ *  case->left    parse tree to execute
+ */
+
+LIST * compile_switch( PARSE * parse, FRAME * frame )
+{
+    LIST * nt = parse_evaluate( parse->left, frame );
+    LIST * result = 0;
+
+    if ( DEBUG_COMPILE )
+    {
+        debug_compile( 0, "switch", frame );
+        list_print( nt );
+        printf( "\n" );
+    }
+
+    /* Step through cases. */
+    for ( parse = parse->right; parse; parse = parse->right )
+    {
+        if ( !glob( parse->left->string, nt ? nt->string : "" ) )
+        {
+            /* Get & exec parse tree for this case. */
+            parse = parse->left->left;
+            result = parse_evaluate( parse, frame );
+            break;
+        }
+    }
+
+    list_free( nt );
+    return result;
+}
+
+
+/*
+ * debug_compile() - printf with indent to show rule expansion.
+ */
+
+static void debug_compile( int which, char * s, FRAME * frame )
+{
+    static int level = 0;
+    static char indent[36] = ">>>>|>>>>|>>>>|>>>>|>>>>|>>>>|>>>>|";
+
+    if ( which >= 0 )
+    {
+        int i;
+
+        print_source_line( frame->procedure );
+
+        i = ( level + 1 ) * 2;
+        while ( i > 35 )
+        {
+            fputs( indent, stdout );
+            i -= 35;
+        }
+
+        printf( "%*.*s ", i, i, indent );
+    }
+
+    if ( s )
+        printf( "%s ", s );
+
+    level += which;
+}