allow reserved Nim keywords as REST params (#15)

This resolves a compilation error when specifying a reserved Nim keyword
as a REST parameter. The error was `node lacks field: strVal`, as the
corresponding identifiers need backticks embedding, e.g., `` `let` ``,
requiring an additional unwrap of `nnkAccQuoted` to get the raw ident.

presto/route.nim

@@ -254,7 +254,7 @@ macro api*(router: RestRouter, meth: static[HttpMethod],
     block:
       var res = newStmtList()
       for (paramName, paramType) in pathArguments:
-        let strName = newStrLitNode(paramName.strVal)
+        let strName = newStrLitNode($paramName)
         res.add(quote do:
           let `paramName` {.used.}: Result[`paramType`, cstring] =
             decodeString(`paramType`, `pathParams`.getString(`strName`))
@@ -266,7 +266,7 @@ macro api*(router: RestRouter, meth: static[HttpMethod],
     block:
       var res = newStmtList()
       for (paramName, paramType) in optionalArguments:
-        let strName = newStrLitNode(paramName.strVal)
+        let strName = newStrLitNode($paramName)
         if isOptionalArg(paramType):
           # Optional arguments which has type `Option[T]`.
           let optType = getOptionType(paramType)

tests/helpers.nim

@@ -166,6 +166,8 @@ proc testValidate*(pattern: string, value: string): int =
       0
     of "{smp3}":
       if value.match({'0' .. '9', 'a' .. 'f', 'A' .. 'F', 'x'}): 0 else: 1
+    of "{let}":
+      if value.match({'0' .. '9'}): 0 else: 1
     else:
       1
   res

tests/testroute.nim

@@ -78,6 +78,39 @@ suite "REST API router & macro tests":
       bytesToString(r3.content.data) == "ok-3"
       bytesToString(r4.content.data) == "ok-4"
 
+  test "Reserved keywords as parameters test":
+    var router = RestRouter.init(testValidate)
+    router.api(MethodGet,
+               "/test/keyword_args/1/{let}") do (
+      `let`: int) -> RestApiResponse:
+        let l = `let`.get()
+        if (l == 999999):
+          return RestApiResponse.response("ok-1", contentType = "test/test")
+
+    router.api(MethodGet,
+               "/test/keyword_args/2/{let}") do (
+      `let`: int,
+      `var`, `block`, `addr`, `custom`: Option[int]) -> RestApiResponse:
+        let l = `let`.get()
+        let v = `var`.get().get()
+        let b = `block`.get().get()
+        let a = `addr`.get().get()
+        let c = custom.get().get()
+        if (l == 888888) and (v == 777777) and (b == 666666) and
+           (a == 555555) and (c == 444444):
+          return RestApiResponse.response("ok-2", contentType = "test/test")
+
+    let r1 = router.sendMockRequest(MethodGet,
+      "http://l.to/test/keyword_args/1/999999")
+    let r2 = router.sendMockRequest(MethodGet,
+      "http://l.to/test/keyword_args/2/888888" &
+      "?var=777777&block=666666&addr=555555&custom=444444")
+    check:
+      r1.kind == RestApiResponseKind.Content
+      bytesToString(r1.content.data) == "ok-1"
+      r2.kind == RestApiResponseKind.Content
+      bytesToString(r2.content.data) == "ok-2"
+
   test "Basic types as parameters test":
     var router = RestRouter.init(testValidate)
     router.api(MethodGet,