fix bug in string interpolation and add more tests

moonscript/compile/value.lua

@@ -88,11 +88,7 @@ value_compile = {
   string = function(self, node)
     local _, delim, inner = unpack(node)
     local end_delim = delim:gsub("%[", "]")
-    if inner then
-      return delim .. inner .. end_delim
-    else
-      return delim .. end_delim
-    end
+    return delim .. inner .. end_delim
   end,
   chain = function(self, node)
     local callee = node[2]

moonscript/compile/value.moon

@@ -46,10 +46,7 @@ value_compile =
   string: (node) =>
     _, delim, inner = unpack node
     end_delim = delim\gsub "%[", "]"
-    if inner
-      delim..inner..end_delim
-    else
-      delim..end_delim
+    delim..inner..end_delim
 
   chain: (node) =>
     callee = node[2]

moonscript/transform.lua

@@ -1136,16 +1136,10 @@ Value = Transformer({
   ["while"] = default_accumulator,
   foreach = default_accumulator,
   string = function(self, node)
-    if #node <= 3 then
-      return node
-    end
     local delim = node[2]
     local convert_part
     convert_part = function(part)
-      if part == nil then
-        return 
-      end
-      if type(part) == "string" then
+      if type(part) == "string" or part == nil then
         return {
           "string",
           delim,
@@ -1163,6 +1157,15 @@ Value = Transformer({
         })
       end
     end
+    if #node <= 3 then
+      return (function()
+        if type(node[3]) == "string" then
+          return node
+        else
+          return convert_part(node[3])
+        end
+      end)()
+    end
     local e = {
       "exp",
       convert_part(node[3])

moonscript/transform.moon

@@ -594,19 +594,24 @@ Value = Transformer {
   foreach: default_accumulator
 
   string: (node) =>
-    return node if #node <= 3
     delim = node[2]
 
     convert_part = (part) ->
-      return if part == nil
-      if type(part) == "string"
+      if type(part) == "string" or part == nil
         {"string", delim, part}
       else
         build.chain { base: "tostring", {"call", {part[2]}} }
 
+    -- reduced to single item
+    if #node <= 3
+      return if type(node[3]) == "string"
+        node
+      else
+        convert_part node[3]
+
     e = {"exp", convert_part node[3]}
 
-    for i=4,#node
+    for i=4, #node
       insert e, ".."
       insert e, convert_part node[i]
     e

tests/inputs/string.moon

@@ -36,22 +36,16 @@ x = "\""
 
 a = "hello #{hello} hello"
 b = "#{hello} hello"
-c = "hello #{hello}"
-d = ""
+c = "hello #{5+1}"
+d = "#{hello world}"
+e = "#{1} #{2} #{3}"
 
-y = "hello" .. "world"
-
-y = [[hello world]]
+f = [[hello #{world} world]]
 
 --
 
 a = 'hello #{hello} hello'
 b = '#{hello} hello'
 c = 'hello #{hello}'
-d = ''
-
-y = 'hello' .. 'world'
-
-y = [[hello world]]
 
 

tests/outputs/string.lua

@@ -18,13 +18,10 @@ x = "\\\n"
 x = "\""
 local a = "hello " .. tostring(hello) .. " hello"
 local b = tostring(hello) .. " hello"
-local c = "hello " .. tostring(hello)
-local d = ""
-local y = "hello" .. "world"
-y = [[hello world]]
+local c = "hello " .. tostring(5 + 1)
+local d = tostring(hello(world))
+local e = tostring(1) .. " " .. tostring(2) .. " " .. tostring(3)
+local f = [[hello #{world} world]]
 a = 'hello #{hello} hello'
 b = '#{hello} hello'
-c = 'hello #{hello}'
-d = ''
-y = 'hello' .. 'world'
-y = [[hello world]]
+c = 'hello #{hello}'