build/src/engine/variable.cpp

/*
 * 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.
 * Copyright 2005 Reece H. Dunn.
 * Copyright 2005 Rene Rivera.
 * Distributed under the Boost Software License, Version 1.0.
 * (See accompanying file LICENSE.txt or copy at
 * https://www.bfgroup.xyz/b2/LICENSE.txt)
 */

/*
 * variable.c - handle Jam multi-element variables.
 *
 * External routines:
 *
 *  var_defines() - load a bunch of variable=value settings
 *  var_get()     - get value of a user defined symbol
 *  var_set()     - set a variable in jam's user defined symbol table.
 *  var_swap()    - swap a variable's value with the given one
 *  var_done()    - free variable tables
 *
 * Internal routines:
 *
 *  var_enter() - make new var symbol table entry, returning var ptr
 *  var_dump()  - dump a variable to stdout
 */

#include "jam.h"
#include "variable.h"

#include "filesys.h"
#include "hash.h"
#include "modules.h"
#include "parse.h"
#include "pathsys.h"
#include "jam_strings.h"
#include "output.h"
#include "strview.h"
#include "value.h"

#include <stdio.h>
#include <stdlib.h>


/*
 * VARIABLE - a user defined multi-value variable
 */

typedef struct _variable VARIABLE ;

struct _variable
{
    OBJECT * symbol;
    LIST   * value;
};

static LIST * * var_enter( struct module_t *, OBJECT * symbol );
static void var_dump( OBJECT * symbol, LIST * value, const char * what );


/*
 * var_defines() - load a bunch of variable=value settings
 *
 * If preprocess is false, take the value verbatim.
 *
 * Otherwise, if the variable value is enclosed in quotes, strip the quotes.
 * Otherwise, if variable name ends in PATH, split value at :'s.
 * Otherwise, split the value at blanks.
 */

void var_defines(struct module_t * module, const char * const * e, int preprocess)
{
	for (; *e; ++e)
	{
		::b2::string_view def(*e);
		::b2::string_view var(def.begin(), def.find('='));
		::b2::string_view val(def.begin() + var.size() + 1);
		b2::jam::variable jam_var { module,
			std::string { var.begin(), var.end() }.c_str() };
		// std::printf(">> var_defines: *e = %s\n", *e);
		// for (auto v : jam_var.get())
		// {
		// 	std::printf("   '%s'\n", v->str());
		// }

		// No value to set var with.
		if (var.size() == def.size()) continue;

		// Skip pre-processing, to just set the raw value.
		if (preprocess == 0)
		{
			jam_var = ::b2::list_ref { ::b2::value_ref { val } };
			continue;
		}

		// Quoted values do not get separator-split. But do get unquoted.
		if (val.size() >= 2 && val.front() == '"' && val.back() == '"')
		{
			jam_var = ::b2::list_ref { ::b2::value_ref {
				val.substr(1, val.size() - 2) } };
			continue;
		}

		// Split on separator, either space or path.
		jam_var = ::b2::list_cref {};
		{
			char split = ' ';
			/* Split *PATH at :'s, not spaces. */
			if (var.ends_with("PATH")
				|| var.ends_with("Path" || var.ends_with("path")))
				split = SPLITPATH;
			/* Do the split. */
			for (::b2::string_view::size_type p0 = 0; p0 < val.size();)
			{
				auto p1 = val.find(split, p0);
				if (p1 == val.npos)
				{
					jam_var += ::b2::value_ref { val.substr(p0) };
					p0 = val.npos;
				}
				else
				{
					jam_var += ::b2::value_ref { val.substr(p0, p1 - p0) };
					p0 = p1 + 1;
				}
			}
		}
	}
}

/* Last returned variable value saved so we may clear it in var_done(). */
static LIST * saved_var = L0;


/*
 * var_get() - get value of a user defined symbol
 *
 * Returns NULL if symbol unset.
 */

LIST * var_get( struct module_t * module, OBJECT * symbol )
{
    LIST * result = L0;
#ifdef OPT_AT_FILES
    /* Some "fixed" variables... */
    if ( object_equal( symbol, constant_TMPDIR ) )
    {
        list_free( saved_var );
        result = saved_var = list_new( object_new( path_tmpdir()->value ) );
    }
    else if ( object_equal( symbol, constant_TMPNAME ) )
    {
        list_free( saved_var );
        result = saved_var = list_new( path_tmpnam() );
    }
    else if ( object_equal( symbol, constant_TMPFILE ) )
    {
        list_free( saved_var );
        result = saved_var = list_new( path_tmpfile() );
    }
    else if ( object_equal( symbol, constant_STDOUT ) )
    {
        list_free( saved_var );
        result = saved_var = list_new( object_copy( constant_STDOUT ) );
    }
    else if ( object_equal( symbol, constant_STDERR ) )
    {
        list_free( saved_var );
        result = saved_var = list_new( object_copy( constant_STDERR ) );
    }
    else
#endif
    {
        VARIABLE * v;
        int n;

        if ( ( n = module_get_fixed_var( module, symbol ) ) != -1 )
        {
            if ( is_debug_varget() )
                var_dump( symbol, module->fixed_variables[ n ], "get" );
            result = module->fixed_variables[ n ];
        }
        else if ( module->variables && ( v = (VARIABLE *)hash_find(
            module->variables, symbol ) ) )
        {
            if ( is_debug_varget() )
                var_dump( v->symbol, v->value, "get" );
            result = v->value;
        }

#ifdef OS_VMS
        else if ( ( module->name && object_equal( module->name, constant_ENVIRON ) )
                  || root_module() == module )
        {
            /* On VMS, when a variable from root or ENVIRON module is not found,
             * explicitly request it from the process.
             * By design, process variables (and logicals) are not made available
             * to C main(), and thus will not get loaded in bulk to root/ENVRON.
             * So we get around it by getting any such variable on first request.
             */
            const char * val = getenv( object_str( symbol ) );

            if ( val )
            {
                struct module_t * environ_module = module;
                char * environ[ 2 ] = { 0 }; /* NULL-terminated */
                string buf[ 1 ];

                if ( root_module() == module )
                {
                    environ_module = bindmodule( constant_ENVIRON );
                }

                string_copy( buf, object_str( symbol ) );
                string_append( buf, "=" );
                string_append( buf, val );

                environ[ 0 ] = buf->value;

                /* Load variable to global module, with splitting, for backward
                 * compatibility. Then to .ENVIRON, without splitting.
                 */
                var_defines( root_module(), environ, 1 );
                var_defines( environ_module, environ, 0 );
                string_free( buf );

                if ( module->variables && ( v = (VARIABLE *)hash_find(
                    module->variables, symbol ) ) )
                {
                    if ( is_debug_varget() )
                        var_dump( v->symbol, v->value, "get" );
                    result = v->value;
                }
            }
        }
#endif
    }
    return result;
}


LIST * var_get_and_clear_raw( module_t * module, OBJECT * symbol )
{
    LIST * result = L0;
    VARIABLE * v;

    if ( module->variables && ( v = (VARIABLE *)hash_find( module->variables,
        symbol ) ) )
    {
        result = v->value;
        v->value = L0;
    }

    return result;
}


/*
 * var_set() - set a variable in Jam's user defined symbol table
 *
 * 'flag' controls the relationship between new and old values of the variable:
 * SET replaces the old with the new; APPEND appends the new to the old; DEFAULT
 * only uses the new if the variable was previously unset.
 *
 * Copies symbol. Takes ownership of value.
 */

void var_set( struct module_t * module, OBJECT * symbol, LIST * value, int flag
    )
{
    LIST * * v = var_enter( module, symbol );

    if ( is_debug_varset() )
        var_dump( symbol, value, "set" );

    switch ( flag )
    {
    case VAR_SET:  /* Replace value */
        list_free( *v );
        *v = value;
        break;

    case VAR_APPEND:  /* Append value */
        *v = list_append( *v, value );
        break;

    case VAR_DEFAULT:  /* Set only if unset */
        if ( list_empty( *v ) )
            *v = value;
        else
            list_free( value );
        break;
    }
}


/*
 * var_swap() - swap a variable's value with the given one
 */

LIST * var_swap( struct module_t * module, OBJECT * symbol, LIST * value )
{
    LIST * * v = var_enter( module, symbol );
    LIST * oldvalue = *v;
    if ( is_debug_varset() )
        var_dump( symbol, value, "set" );
    *v = value;
    return oldvalue;
}


/*
 * var_enter() - make new var symbol table entry, returning var ptr
 */

static LIST * * var_enter( struct module_t * module, OBJECT * symbol )
{
    int found;
    VARIABLE * v;
    int n;

    if ( ( n = module_get_fixed_var( module, symbol ) ) != -1 )
        return &module->fixed_variables[ n ];

    if ( !module->variables )
        module->variables = hashinit( sizeof( VARIABLE ), "variables" );

    v = (VARIABLE *)hash_insert( module->variables, symbol, &found );
    if ( !found )
    {
        v->symbol = object_copy( symbol );
        v->value = L0;
    }

    return &v->value;
}


/*
 * var_dump() - dump a variable to stdout
 */

static void var_dump( OBJECT * symbol, LIST * value, const char * what )
{
    out_printf( "%s %s = ", what, object_str( symbol ) );
    list_print( value );
    out_printf( "\n" );
}


/*
 * var_done() - free variable tables
 */

static void delete_var_( void * xvar, void * data )
{
    VARIABLE * const v = (VARIABLE *)xvar;
    object_free( v->symbol );
    list_free( v->value );
}

void var_done( struct module_t * module )
{
    list_free( saved_var );
    saved_var = L0;
    hashenumerate( module->variables, delete_var_, 0 );
    hash_free( module->variables );
}