1 files changed, 74 insertions, 0 deletions
diff --git a/tests/macros/tstringinterp.nim b/tests/macros/tstringinterp.nim
new file mode 100644
index 000000000..a500ed56e
--- /dev/null
+++ b/tests/macros/tstringinterp.nim
@@ -0,0 +1,74 @@
+discard """
+  file: "tstringinterp.nim"
+  output: "Hello Alice, 64 | Hello Bob, 10$"
+"""
+
+import macros, parseutils, strutils
+
+proc concat(strings: varargs[string]): string =
+  result = newString(0)
+  for s in items(strings): result.add(s)
+
+template processInterpolations(e: expr) =
+  var s = e[1].strVal
+  for f in interpolatedFragments(s):
+    case f.kind
+    of ikStr:         addString(f.value)
+    of ikDollar:      addDollar()
+    of ikVar, ikExpr: addExpr(newCall("$", parseExpr(f.value)))
+
+macro formatStyleInterpolation(e: expr): expr =
+  let e = callsite()
+  var 
+    formatString = ""
+    arrayNode = newNimNode(nnkBracket)
+    idx = 1
+
+  proc addString(s: string) =
+    formatString.add(s)
+
+  proc addExpr(e: PNimrodNode) =
+    arrayNode.add(e)
+    formatString.add("$" & $(idx))
+    inc idx
+
+  proc addDollar() =
+    formatString.add("$$")
+    
+  processInterpolations(e)
+
+  result = parseExpr("\"x\" % [y]")
+  result[1].strVal = formatString
+  result[2] = arrayNode
+
+macro concatStyleInterpolation(e: expr): expr =
+  let e = callsite()
+  var args: seq[PNimrodNode]
+  newSeq(args, 0)
+
+  proc addString(s: string)    = args.add(newStrLitNode(s))
+  proc addExpr(e: PNimrodNode) = args.add(e)
+  proc addDollar()             = args.add(newStrLitNode"$")
+
+  processInterpolations(e)
+
+  result = newCall("concat", args)
+
+###
+
+proc sum(a, b, c: int): int =
+  return (a + b + c)
+
+var 
+  alice = "Alice"
+  bob = "Bob"
+  a = 10
+  b = 20
+  c = 34
+
+var
+  s1 = concatStyleInterpolation"Hello ${alice}, ${sum(a, b, c)}"
+  s2 = formatStyleInterpolation"Hello ${bob}, ${sum(alice.len, bob.len, 2)}$$"
+
+write(stdout, s1 & " | " & s2)
+