Include support in schemas

src/preserves/schemas.nim

@@ -5,6 +5,8 @@
 ## https://preserves.gitlab.io/preserves/preserves-schema.html
 
 import std/[parseutils, macros, strutils, tables]
+from os import absolutePath, isAbsolute, parentDir
+
 import npeg
 import ../preserves, ./parse, ./pegs
 
@@ -65,6 +67,7 @@ type
     definitions*: OrderedTable[string, SchemaNode]
 
   ParseState = object
+    filepath: string
     stack: Stack
     schema: Schema
 
@@ -210,16 +213,21 @@ const parser = peg("Schema", p: ParseState):
   Clause <- (Version | EmbeddedTypeName | Include | Definition) * S * '.'
 
   Version <- "version" * S * >(*Digit):
-    if not p.schema.version == 0: fail()
     discard parseInt($1, p.schema.version)
+    if p.schema.version != 1: fail()
 
   EmbeddedTypeName <- "embeddedType" * S * >("#f" | Ref):
     if p.schema.embeddedType != "": fail()
     if $1 != "#f": p.schema.embeddedType = $1
 
-  Include <- "include" * S * >(+Alnum):
-    # TODO: may be relative or absolute
-    match(readFile $1, p)
+  Include <- "include" * S * (>(+Alnum) | ('"' * >(@'"'))):
+    var ip = ParseState(
+      schema: p.schema,
+      filepath:
+        if isAbsolute($1): $1
+        else: absolutePath($1, p.filepath.parentDir))
+    ip.filePath.setLen(ip.filePath.high)
+    match(readFile ip.filepath, ip)
 
   Definition <- >id * S * '=' * S * (OrPattern | AndPattern | Pattern):
     if p.schema.definitions.hasKey $1:
@@ -409,11 +417,11 @@ const parser = peg("Schema", p: ParseState):
 proc match(text: string; p: var ParseState) =
   let match = parser.match(text, p)
   if not match.ok:
-    raise newException(ValueError, "failed to parse Preserves schema:\n" & text[0..<match.matchMax])
+    raise newException(ValueError, "failed to parse " & p.filepath & ":\n" & text[0..<match.matchMax])
 
-proc parsePreservesSchema*(text: string): Schema =
+proc parsePreservesSchema*(text, filepath: string): Schema =
   ## Parse a Preserves schema into an abstract syntax tree represented as a `Preserve`.
-  var p: ParseState
+  var p = ParseState(filepath: filepath)
   new p.schema
   match(text, p)
   result = p.schema