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Generator functions#384

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tomblind merged 16 commits intoTypeScriptToLua:masterfrom
andreiradu:yeld_statement
Feb 10, 2019
Merged

Generator functions#384
tomblind merged 16 commits intoTypeScriptToLua:masterfrom
andreiradu:yeld_statement

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@andreiradu andreiradu commented Feb 8, 2019 •
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One particular issue is that calling iterator.next(42) transpiles to iterator:next(42), which in turn means that the corresponding coroutine.yield() will return iterator, 42. I've made it so let a = yield() transpiles to local _, a = coroutine.yield() to account for that.

function* seq() {
    let a = yield 1;
    return a;
}
const gen = seq();

will transpile to:

seq = function()
    local __co = coroutine.create(function()
        local a = coroutine.yield(1);
        return a;
    end);
    __it = {next = function(___, ...)
        local __err, __value = coroutine.resume(__co, ...);
        if not __err then
            error(__value);
        end
        return {done = coroutine.status(__co) == "dead", value = __value};
    end};
    __it[Symbol.iterator] = function()
        return __it;
    end;
    return __it;
end;
local gen = seq();

Perryvw
Perryvw reviewed Feb 8, 2019
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src/LuaTransformer.ts Outdated
tstl.createTableIndexExpression(itIdentifier, symbolIterator),
tstl.createFunctionExpression(tstl.createBlock([tstl.createReturnStatement([itIdentifier])]))),
tstl.createReturnStatement([itIdentifier])]
);
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@Perryvw Perryvw Feb 8, 2019

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Could you refactor this entire if block to transformGeneratorFunctionDeclaration()? This is quite hard to read, some intermediate variables wouldn't hurt. It would also be nice if you could try to stick a little closer to how the rest of the code and long expressions are formatted. (see this.transformFunctionBody at line 1078 for example)

tomblind
tomblind requested changes Feb 9, 2019
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Overall, a great feature PR - mostly just needs some changes for code consistency. Also, I think it would be good to have a test using a for...of loop, since that's the most likely use-case.

tomblind
tomblind requested changes Feb 10, 2019
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src/LuaTransformer.ts
tstl.createTableIndexExpression(tstl.createIdentifier("coroutine"), tstl.createStringLiteral("yield")),
expression.expression?[this.transformExpression(expression.expression)]:[], expression);
}
public transformReturn(statement: ts.ReturnStatement): tstl.Statement {
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@tomblind tomblind Feb 10, 2019

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Same as above

@tomblind tomblind merged commit ed87cb6 into TypeScriptToLua:master Feb 10, 2019
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@Perryvw Perryvw Perryvw approved these changes

@tomblind tomblind tomblind approved these changes

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3 participants

@andreiradu @Perryvw @tomblind