write-php-ops.js

// Utility to write out the opcode mapping from `bytecode-table.js`
// as a PHP file.
//
// Run it under `node` with the CLI in `bin/write-php-ops.js`
define(['./bytecode-table'], function(bytecode_table) {
    var bops = [];
    while(true) {
        var bc = bytecode_table.for_num(bops.length);
        if (!bc) { break; }
        bops.push(bc);
    }
    var comma = function(i) { return (i < (bops.length-1)) ? ',' : ''; };
    var phpName = function(bc) {
        var name = bc.name.toUpperCase();
        if (name==='2DUP') { return 'DUP2'; }
        return name;
    };

    console.log('<?php');
    console.log('// generated by TurtleScript write-php-ops.js');
    console.log('');
    console.log('namespace Wikimedia\\PhpTurtle;');
    console.log('');

    console.log('class Op {');
    // ## Emit `Op` enumeration.
    bops.forEach(function(bc, i) {
        console.log('\tpublic const ' + phpName(bc) + ' = ' + i + ';');
    });
    console.log('');

    var buildSwitch = function(fn) {
        console.log('\t\tswitch ( $op ) {');
        var group = [];
        bops.forEach(function(bc) {
            var val = fn(bc);
            if (typeof val === 'function') {
                console.log('\t\tcase self::' + phpName(bc) + ':');
                console.log('\t\t\treturn ' + val() + ';');
            } else {
                if (group[val]===undefined) { group[val] = []; }
                group[val].push(bc);
            }
        });
        var i = 1;
        while (i < group.length) {
            if (group[i] !== undefined && group[i].length > 0) {
                group[i].forEach(function(bc) {
                    console.log('\t\tcase self::' + phpName(bc) + ':');
                });
                console.log('\t\t\treturn ' + i + ';');
            }
            i+=1;
        }
        if (group[0] !== undefined && group[0].length > 0) {
            console.log('\t\tdefault:');
            console.log('\t\t\treturn 0;');
        }
        console.log('\t\t}');
    };

    // ## Emit `Op` functions.
    console.log('\t/**');
    console.log('\t * Return the number of arguments used for the given opcode.');
    console.log('\t * @param int $op The opcode');
    console.log('\t * @return int The number of arguments required');
    console.log('\t */');
    console.log('\tpublic static function args( int $op ): int {');
    buildSwitch(function(bc) { return bc.args; });
    console.log('\t}');
    console.log('');

    console.log('\t/**');
    console.log('\t * Return the number of stack slots pushed by the given opcode.');
    console.log('\t * @param int $op The opcode');
    console.log('\t * @return int The number of stack slots pushed');
    console.log('\t */');
    console.log('\tpublic static function stackpush( int $op ): int {');
    buildSwitch(function(bc) { return bc.stackpush(); });
    console.log('\t}');
    console.log('');

    console.log('\t/**');
    console.log('\t * Return the number of stack slots popped by the given opcode.');
    console.log('\t * @param int $op The opcode');
    console.log('\t * @param array $args The arguments to that opcode');
    console.log('\t * @return int The number of stack slots popped');
    console.log('\t */');
    console.log('\tpublic static function stackpop( int $op, array $args ): int {');
    buildSwitch(function(bc) {
        if (bc.name === 'invoke') {
            return (function() { return '$args[0] + 2'; });
        }
        return bc.stackpop();
    });
    console.log('\t}');
    console.log('');

    console.log('\t/**');
    console.log('\t * Return the human-readable name for the given opcode.');
    console.log('\t * @param int $op The opcode');
    console.log('\t * @return string The name of the opcode');
    console.log('\t */');
    console.log('\tpublic static function name( int $op ): string {');
    buildSwitch(function(bc) { return (function() {
        return '"' + bc.name + '"';
    }); });
    console.log('\t}');

    console.log('}');
});