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Add if expression support to the compiler #202

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58 changes: 58 additions & 0 deletions src/prometheus/compiler/compiler.lua
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Original file line number Diff line number Diff line change
Expand Up @@ -2359,6 +2359,64 @@ function Compiler:compileExpression(expression, funcDepth, numReturns)
return regs;
end

if(expression.kind == AstKind.IfElseExpression) then
local posState = self.registers[self.POS_REGISTER];
self.registers[self.POS_REGISTER] = self.VAR_REGISTER;

local regs = {};
for i=1, numReturns do
regs[i] = self:allocRegister();
if(i ~= 1) then
self:addStatement(self:setRegister(scope, regs[i], Ast.NilExpression()), {regs[i]}, {}, false);
end
end

local resReg = regs[1];
local tmpReg;

if posState then
tmpReg = self:allocRegister(false);
self:addStatement(self:copyRegisters(scope, {tmpReg}, {self.POS_REGISTER}), {tmpReg}, {self.POS_REGISTER}, false);
end

local conditionReg = self:compileExpression(expression.condition, funcDepth, 1)[1];

local trueBlock, falseBlock, finalBlock = self:createBlock(), self:createBlock(), self:createBlock();

self:addStatement(self:setRegister(scope, self.POS_REGISTER, Ast.OrExpression(Ast.AndExpression(self:register(scope, conditionReg), Ast.NumberExpression(trueBlock.id)), Ast.NumberExpression(falseBlock.id))), {self.POS_REGISTER}, {conditionReg}, false);
self:freeRegister(conditionReg, false);

do
self:setActiveBlock(trueBlock);
local scope = trueBlock.scope;
local trueReg = self:compileExpression(expression.true_value, funcDepth, 1)[1];
self:addStatement(self:copyRegisters(scope, {resReg}, {trueReg}), {resReg}, {trueReg}, false);
self:freeRegister(trueReg, false);
self:addStatement(self:setRegister(scope, self.POS_REGISTER, Ast.NumberExpression(finalBlock.id)), {self.POS_REGISTER}, {}, false);
end

do
self:setActiveBlock(falseBlock);
local scope = falseBlock.scope;
local falseReg = self:compileExpression(expression.false_value, funcDepth, 1)[1];
self:addStatement(self:copyRegisters(scope, {resReg}, {falseReg}), {resReg}, {falseReg}, false);
self:freeRegister(falseReg, false);
self:addStatement(self:setRegister(scope, self.POS_REGISTER, Ast.NumberExpression(finalBlock.id)), {self.POS_REGISTER}, {}, false);
end

self.registers[self.POS_REGISTER] = posState;

self:setActiveBlock(finalBlock);
scope = finalBlock.scope;

if tmpReg then
self:addStatement(self:copyRegisters(scope, {self.POS_REGISTER}, {tmpReg}), {self.POS_REGISTER}, {tmpReg}, false);
self:freeRegister(tmpReg, false);
end

return regs;
end

logger:error(string.format("%s is not an compliable expression!", expression.kind));
end

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4 changes: 2 additions & 2 deletions src/prometheus/visitast.lua
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Original file line number Diff line number Diff line change
Expand Up @@ -237,8 +237,8 @@ function visitExpression(expression, previsit, postvisit, data)
end
if(expression.kind == AstKind.IfElseExpression) then
expression.condition = visitExpression(expression.condition, previsit, postvisit, data);
expression.true_expr = visitExpression(expression.true_expr, previsit, postvisit, data);
expression.false_expr = visitExpression(expression.false_expr, previsit, postvisit, data);
expression.true_value = visitExpression(expression.true_value, previsit, postvisit, data);
expression.false_value = visitExpression(expression.false_value, previsit, postvisit, data);
end

if(type(postvisit) == "function") then
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