Add some initial E2 tests

data/expression2/tests/parsing.txt

@@ -0,0 +1,88 @@
+@inputs In
+@outputs Out
+
+local A = 0
+
+if (A) { A = 0 }
+if (A) { A = 0 } else { A = 0 }
+if (A) { A = 0 } elseif (A) { A = 0 }
+if (A) { A = 0 } elseif (A) { A = 0 }
+
+while (A) { A = 0 }
+
+for (B = 1, 2) { A = 0 }
+for (B = 1, 2, 3) { A = 0 }
+
+foreach (K, V: number = array(1, 2, 3)) { A = 0 }
+
+while (A) { break }
+while (A) { continue }
+
+A++
+A--
+A += 1
+A -= 1
+A *= 1
+A /= 1
+
+local B = vec()
+B[1] = 2
+
+switch (A) {
+    case A + A,
+        A = 0
+        A = 0
+    case A + A + A,
+        A = 0
+        break
+    default,
+        A = 0
+}
+
+function f() {}
+function void f() {}
+function void f() { return }
+function number g() { return 0 }
+function number f(X) { return X }
+function vector f(X: vector) { return X }
+function number f(X, Y) { return X + Y }
+function number f(X, Y: vector) { return X }
+function number f([X Y]) { return X + Y }
+function number f([X Y]: number) { return X + Y }
+
+A ? A : A
+A ?: A
+A | A
+A & A
+A || A
+A && A
+A ^^ A
+A == A
+A != A
+A > A
+A < A
+A >= A
+A <= A
+A << A
+A >> A
+A + A
+A - A
+A * A
+A / A
+A % A
+A ^ A
++A
+-A
+!A
+
+array():count()
+array()[0, number]
+(A)
+0
+"foo"
+~In
+$In
+->In
+A
+
+table(1 = 1, 2 = 2)

data/expression2/tests/regressions/1975.txt

@@ -0,0 +1,11 @@
+vec() * 0
+0 * vec()
+
+local Calls = 0
+function number f() {
+    Calls++
+    return 1
+}
+f() * 0
+0 * f()
+assert(Calls == 2)

lua/entities/gmod_wire_expression2/core/core.lua

@@ -318,6 +318,14 @@ e2function void error( string reason )
 	error(reason, 2)
 end
 
+e2function void assert(condition)
+	if not condition then error("assert failed", 2) end
+end
+
+e2function void assert(condition, string reason)
+	if not condition then error(reason, 2) end
+end
+
 --------------------------------------------------------------------------------
 
 __e2setcost(100) -- approximation

lua/wire/client/e2descriptions.lua

@@ -824,6 +824,8 @@ E2Helper.Descriptions["setName(e:s)"] = "Set the name of another E2 or component
 E2Helper.Descriptions["cpuUsage()"] = "Returns the average time per tick the server spends running this E2, in seconds (multiply it by 1000000 to get the same value as is displayed on the E2 overlay)"
 E2Helper.Descriptions["cpuUsage(e:)"] = "Returns the average time per tick the server spends running the specified E2, in seconds (multiply it by 1000000 to get the same value as is displayed on the E2 overlay)"
 E2Helper.Descriptions["error(s)"] = "Shuts down the E2 with specified script error message"
+E2Helper.Descriptions["assert(n)"] = "If the argument is 0, shut down the E2 with an error message"
+E2Helper.Descriptions["assert(ns)"] = "If the first argument is 0, shut down the E2 with the given error message string"
 E2Helper.Descriptions["reset()"] = "Reset the expression itself as if it was just spawned, stops execution"
 E2Helper.Descriptions["exit()"] = "Stops the execution of any code after it"
 E2Helper.Descriptions["getCode()"] = "Returns the code of the E2 as a string"

lua/wire/default_data_decompressor.lua

@@ -1,8 +1,13 @@
 -- Garry has imposed a file extension whitelist for the Steam Workshop which does not permit the dangerous format .txt
 -- Therefore, we must store our .txt's in default_data_files.lua, and then extract them when first run
 
+local ignored_dirs = {
+	["expression2/tests"] = true,
+}
+
 -- Compress all files in addons/wire/data recursively into 1 json string
 local function ReadDir(root)
+	if ignored_dirs[root] then return nil end
 	local tab = {}
 	local files,dirs = file.Find("addons/wire/data/"..root.."*","GAME")
 	for _, f in pairs(files) do
@@ -16,7 +21,7 @@ local function ReadDir(root)
 	return tab
 end
 -- Uncomment and Rename this file to wire/lua/wire/default_data_files.lua to update it
-//file.Write("default_data_files.txt", "//"..util.TableToJSON(ReadDir("")))
+-- file.Write("default_data_files.txt", "//"..util.TableToJSON(ReadDir("")))
 
 -- Decompress the json string wire/lua/wire/default_data_files.lua into the corresponding 36+ default data files
 local function WriteDir(tab)
@@ -34,7 +39,7 @@ if not file.Exists("expression2/_helloworld_.txt", "DATA") then
 	local compressed = file.Read("wire/default_data_files.lua","LUA")
 	-- The client cannot read lua files sent by the server (for security?), so clientside this'll only work
 	-- if the client actually has Wiremod installed, though with workshop autodownload that'll be common
-	if compressed != nil then
+	if compressed ~= nil then
 		WriteDir(util.JSONToTable(string.sub(compressed, 3)))
 	end
 end