Added a way to intercept output.

Macros can use outputLua() and co. instead of returning code.

Author: ReFreezed

preprocess.lua

@@ -26,6 +26,7 @@
 	- getCurrentPathIn, getCurrentPathOut
 	- getOutputSoFar, getOutputSizeSoFar, getCurrentLineNumberInOutput
 	- outputValue, outputLua, outputLuaTemplate
+	- startInterceptingOutput, stopInterceptingOutput
 	Search this file for 'EnvironmentTable' for more info.
 
 	Exported stuff from the library:
@@ -188,7 +189,8 @@ local isRunningMeta            = false
 local currentPathIn            = ""
 local currentPathOut           = ""
 local metaPathForErrorMessages = ""
-local outputFromMeta           = nil
+local outputFromMetaStack      = nil
+local outputFromMeta           = nil -- Top item in outputFromMetaStack.
 local canOutputNil             = true
 local fastStrings              = false
 
@@ -1321,6 +1323,8 @@ end
 
 
 -- :EnvironmentTable
+----------------------------------------------------------------
+
 metaEnv = copyTable(_G, true) -- Include all standard Lua stuff.
 metaEnv._G = metaEnv
 
@@ -1485,7 +1489,7 @@ end
 --   Raises an error if no file or string is being processed.
 function metaFuncs.getOutputSoFar(asTable)
 	errorIfNotRunningMeta(2)
-	return asTable and copyArray(outputFromMeta) or table.concat(outputFromMeta)
+	return asTable and copyArray(outputFromMetaStack[1]) or table.concat(outputFromMetaStack[1]) -- Should there be a way to get the contents of outputFromMeta etc.? :GetMoreOutputFromStack
 end
 
 -- getOutputSizeSoFar()
@@ -1497,7 +1501,7 @@ function metaFuncs.getOutputSizeSoFar()
 
 	local size = 0
 
-	for _, lua in ipairs(outputFromMeta) do
+	for _, lua in ipairs(outputFromMetaStack[1]) do -- :GetMoreOutputFromStack
 		size = size + #lua
 	end
 
@@ -1512,7 +1516,7 @@ function metaFuncs.getCurrentLineNumberInOutput()
 
 	local ln = 1
 
-	for _, lua in ipairs(outputFromMeta) do
+	for _, lua in ipairs(outputFromMetaStack[1]) do -- :GetMoreOutputFromStack
 		ln = ln + countString(lua, "\n", true)
 	end
 
@@ -1825,9 +1829,34 @@ function metaFuncs.concatTokens(tokens)
 	return _concatTokens(tokens, nil, false, nil, nil)
 end
 
+-- startInterceptingOutput()
+--   startInterceptingOutput( )
+--   Start intercepting output until stopInterceptingOutput() is called.
+--   The function can be called multiple times to intercept interceptions.
+function metaFuncs.startInterceptingOutput()
+	errorIfNotRunningMeta(2)
+
+	outputFromMeta = {}
+	tableInsert(outputFromMetaStack, outputFromMeta)
+end
+
+-- stopInterceptingOutput()
+--   luaString = stopInterceptingOutput( )
+--   Stop intercepting output.
+function metaFuncs.stopInterceptingOutput()
+	errorIfNotRunningMeta(2)
+
+	local interceptedLua = tableRemove(outputFromMetaStack)
+	outputFromMeta       = outputFromMetaStack[#outputFromMetaStack] or error("Called stopInterceptingOutput() before calling startInterceptingOutput()", 2)
+
+	return table.concat(interceptedLua)
+end
+
 -- Extra stuff used by the command line program:
 metaFuncs.tryToFormatError = tryToFormatError
 
+----------------------------------------------------------------
+
 
 
 for k, v in pairs(metaFuncs) do  metaEnv[k] = v  end
@@ -1845,6 +1874,23 @@ function metaEnv.__ASSERTLUA(lua)
 	return lua
 end
 
+local function finalizeMacro(lua)
+	if lua == nil then
+		return (metaFuncs.stopInterceptingOutput())
+	elseif type(lua) ~= "string" then
+		error("[Macro] Value is not Lua code.", 2)
+	elseif outputFromMeta[1] then
+		error("[Macro] Got Lua code from both value expression and outputLua(). Only one method may be used.", 2) -- It's also possible interception calls are unbalanced.
+	else
+		metaFuncs.stopInterceptingOutput() -- Returns "" because nothing was outputted.
+		return lua
+	end
+end
+function metaEnv.__MACRO()
+	metaFuncs.startInterceptingOutput()
+	return finalizeMacro
+end
+
 function metaEnv.__EVALSYMBOL(v)
 	if type(v) == "function" then
 		v = v()
@@ -2152,13 +2198,18 @@ end
 
 local function expandMacro(tokens, fileBuffers, tokenStack, macroStartTok, isNested)
 	-- @Robustness: Make sure key tokens came from the same source file.
+
 	-- Add '!!(' for start of preprocessor block.
-	if isNested then
-		tableInsert(tokens, newTokenAt({type="identifier", value="__ASSERTLUA", representation="__ASSERTLUA"}, macroStartTok))
-	else
-		tableInsert(tokens, newTokenAt({type="pp_entry", value="!!", representation="!!", double=true}, macroStartTok))
+	if not isNested then
+		tableInsert(tokens, newTokenAt({type="pp_entry",    value="!!", representation="!!", double=true}, macroStartTok))
+		tableInsert(tokens, newTokenAt({type="punctuation", value="(",  representation="("              }, macroStartTok))
 	end
-	tableInsert(tokens, newTokenAt({type="punctuation", value="(", representation="("}, macroStartTok))
+
+	-- Start macro wrapper.
+	tableInsert(tokens, newTokenAt({type="identifier",  value="__MACRO",      representation="__MACRO"     }, macroStartTok))
+	tableInsert(tokens, newTokenAt({type="punctuation", value="(",            representation="("           }, macroStartTok))
+	tableInsert(tokens, newTokenAt({type="punctuation", value=")",            representation=")"           }, macroStartTok))
+	tableInsert(tokens, newTokenAt({type="punctuation", value="(",            representation="("           }, macroStartTok))
 
 	--
 	-- Callee.
@@ -2496,8 +2547,13 @@ local function expandMacro(tokens, fileBuffers, tokenStack, macroStartTok, isNes
 	-- End.
 	--
 
-	-- Add ')' for end of preprocessor block.
+	-- End macro wrapper.
 	tableInsert(tokens, newTokenAt({type="punctuation", value=")", representation=")"}, tokens[#tokens]))
+
+	-- Add ')' for end of preprocessor block.
+	if not isNested then
+		tableInsert(tokens, newTokenAt({type="punctuation", value=")", representation=")"}, tokens[#tokens]))
+	end
 end
 
 local function doLateExpansionsMacros(tokensToExpand, fileBuffers, params, stats)
@@ -2969,6 +3025,7 @@ local function _processFileOrString(params, isFile)
 
 	metaPathForErrorMessages = params.pathMeta or "<meta>"
 	outputFromMeta           = {}
+	outputFromMetaStack      = {outputFromMeta}
 	canOutputNil             = params.canOutputNil ~= false
 	fastStrings              = params.fastStrings
 
@@ -2994,6 +3051,10 @@ local function _processFileOrString(params, isFile)
 		os.remove(params.pathMeta)
 	end
 
+	if outputFromMetaStack[2] then
+		error("Called startInterceptingOutput() more times than stopInterceptingOutput().")
+	end
+
 	local lua = table.concat(outputFromMeta)
 	--[[ :PrintCode
 	print("=OUTPUT=============================")
@@ -3002,6 +3063,7 @@ local function _processFileOrString(params, isFile)
 	--]]
 
 	metaPathForErrorMessages = ""
+	outputFromMetaStack      = nil
 	outputFromMeta           = nil
 	canOutputNil             = true
 
@@ -3103,6 +3165,7 @@ local function processFileOrString(params, isFile)
 	currentPathIn            = ""
 	currentPathOut           = ""
 	metaPathForErrorMessages = ""
+	outputFromMetaStack      = nil
 	outputFromMeta           = nil
 	canOutputNil             = true
 	fastStrings              = false

tests/quickTest.lua2p

@@ -142,6 +142,18 @@ local  n    = @@t.field[keys[1]]:method(58)
 local n1 = @@ADD1!(43-2)
 local n2 = @@ADD1!!("43-2")
 
+!local function FOO1(x)  return x      end
+!local function FOO2(x)  outputLua(x)  end
+local x = 7
+local y = @@FOO1(x)
+local y = @@FOO2(x)
+
+!startInterceptingOutput()
+a          = some
+other      = 500921
+!local lua = stopInterceptingOutput():gsub("%a+", "%0Derp")
+!!(lua)
+
 
 
 -- Symbols.

tests/quickTest.output.lua

@@ -102,6 +102,13 @@ local n = 58
 local n1 = 41+1
 local n2 = 43-2+1
 
+local x = 7
+local y = x
+local y = x
+
+aDerp     = someDerp
+otherDerp = 500921
+
 
 
 -- Symbols

tests/suite.lua

@@ -369,6 +369,13 @@ doTest("Macros", function()
 
 	-- Invalid: Nested code block in macro.
 	assert(not pp.processString{ code=[[  !(function ECHO(v) return v end)  v = @@ECHO( !!( !(1) ) )  ]]})
+
+	-- Using outputLua().
+	assertCodeOutput(assert(pp.processString{ code=[[  !(function Y() return   ("y") end)  x = @@Y()  ]]}), [[x = y]])
+	assertCodeOutput(assert(pp.processString{ code=[[  !(function Y() outputLua("y") end)  x = @@Y()  ]]}), [[x = y]])
+
+	-- Invalid: Both using outputLua() and returning code.
+	assert(not pp.processString{ code=[[  !(function Y() outputLua("y") ; return "z" end)  x = @@Y()  ]]})
 end)
 
 doTest("Preprocessor symbols", function()
@@ -514,6 +521,22 @@ doTest("Serialize", function()
 	assertCodeOutput(luaOut, [[{a=2,f=176,z=99}]]) -- Note: Table keys should be sorted.
 end)
 
+doTest("Output interception", function()
+	local pp = ppChunk()
+
+	local luaOut = assert(pp.processString{ code=[[
+		!startInterceptingOutput()
+		local foo  = bar
+		!local lua = stopInterceptingOutput():gsub("(%a+) *= *(%a+)", "%2 = %1")
+		$lua
+	]] })
+	assertCodeOutput(luaOut, [[local bar = foo]])
+
+	-- Invalid: Unbalanced interception start/stop calls.
+	assert(not pp.processString{ code=[[ !startInterceptingOutput() ]]})
+	assert(not pp.processString{ code=[[ !stopInterceptingOutput()  ]]})
+end)
+
 
 
 addLabel("Command line")