Move preserves/parse module into preserves

Some macros in preserves call `parsePreserves` so include that
proc implicitly.

src/preserves.nim

@@ -256,8 +256,7 @@ func step*(pr, idx: Preserve): Option[Preserve] =
   ## Step into `pr` by index `idx`.
   ## Works for sequences, records, and dictionaries.
   runnableExamples:
-    import options
-    import preserves, preserves/parse
+    import std/options
     assert step(parsePreserves("""<foo 1 2>"""), 1.toPreserve) == some(2.toPreserve)
     assert step(parsePreserves("""{ foo: 1 bar: 2}"""), "foo".toSymbol) == some(1.toPreserve)
     assert step(parsePreserves("""[ ]"""), 1.toPreserve) == none(Preserve[void])
@@ -786,7 +785,6 @@ proc fromPreserve*[T, E](v: var T; pr: Preserve[E]): bool =
   ## trace is printing during `fromPreserve`.
   # TODO: {.raises: [].}
   runnableExamples:
-    import preserves, preserves/parse
     type Foo {.preservesRecord: "foo".} = object
       x, y: int
     var foo: Foo
@@ -967,7 +965,7 @@ proc preserveTo*(pr: Preserve; T: typedesc): Option[T] =
   ## Reverse of `toPreserve`.
   # TODO: {.raises: [].}
   runnableExamples:
-    import std/options, preserves, preserves/parse
+    import std/options
     type Foo {.preservesRecord: "foo".} = object
       x, y: int
 
@@ -1136,3 +1134,5 @@ proc concat[E](result: var string; pr: Preserve[E]) =
 
 proc `$`*(pr: Preserve): string = concat(result, pr)
   ## Generate the textual representation of ``pr``.
+
+include ./preserves/private/parse

src/preserves/pegs.nim

@@ -1,6 +1,8 @@
 # SPDX-FileCopyrightText: 2021 ☭ Emery Hemingway
 # SPDX-License-Identifier: Unlicense
 
+## NPEG rules for Preserves.
+
 import npeg, npeg/lib/utf8
 
 when defined(nimHasUsed): {.used.}

src/preserves/private/parse.nim

@@ -1,9 +1,11 @@
 # SPDX-FileCopyrightText: 2021 ☭ Emery Hemingway
 # SPDX-License-Identifier: Unlicense
 
-import std/[base64, parseutils, sets, strutils, tables]
+# this module is included in ../../preserves.nim
+
+import std/[parseutils, strutils]
 import npeg
-import ../preserves, ./pegs
+import ../pegs
 
 type
   Value = Preserve[void]
@@ -15,6 +17,9 @@ proc shrink(stack: var Stack; n: int) = stack.setLen(stack.len - n)
 template pushStack(v: Value) = stack.add((v, capture[0].si))
 
 proc parsePreserves*(text: string): Preserve[void] {.gcsafe.} =
+  ## Parse a text-encoded Preserves `string` to a `Preserve` value.
+  runnableExamples:
+    assert parsePreserves"[ 1 2 3 ]" == [ 1, 2, 3 ].toPreserve
   const pegParser = peg("Document", stack: Stack):
     # Override rules from pegs.nim
 
@@ -105,8 +110,6 @@ proc parsePreserves*(text: string): Preserve[void] {.gcsafe.} =
   stack.pop.value
 
 proc parsePreserves*(text: string; E: typedesc): Preserve[E] {.gcsafe.} =
+  ## Parse a text-encoded Preserves `string` to a `Preserve[E]` value for embedded type `E`.
   when E is void: parsePreserves(text)
   else: mapEmbeds(parsePreserves(text), E)
-
-when isMainModule:
-  assert(parsePreserves("#f") == Preserve())