Schemas: fix embedded pattern

src/preserves/schemas.nim

@@ -47,6 +47,8 @@ type
     of snkAny: discard
     of snkAtom:
       atom*: AtomKind
+    of snkEmbedded:
+      embed*: SchemaNode
     of snkLiteral:
       value*: Preserve
     of snkNamed:
@@ -90,7 +92,7 @@ proc `$`*(n: SchemaNode): string =
   of snkAny: result.add "any"
   of snkAtom: result.add $n.atom
   of snkEmbedded:
-    result.add "#!" & $n.nodes[0]
+    result.add "#!" & $n.embed
   of snkLiteral:
     case n.value.kind
     of pkBoolean, pkFloat, pkDouble, pkSignedInteger, pkString, pkByteString, pkSymbol:
@@ -221,6 +223,8 @@ const parser = peg("Schema", p: ParseState):
     match(readFile $1, p)
 
   Definition <- >id * S * '=' * S * (OrPattern | AndPattern | Pattern):
+    if p.schema.definitions.hasKey $1:
+      raise newException(ValueError, "duplicate definition of " & $1)
     p.schema.definitions[$1] = popStack()
     p.stack.setLen(0)
 
@@ -304,8 +308,8 @@ const parser = peg("Schema", p: ParseState):
     of "symbol": n.atom = akSymbol
     pushStack n
 
-  EmbeddedPattern <- "embedded":
-    let n = newSchemaNode(snkEmbedded)
+  EmbeddedPattern <- "#!" * SimplePattern:
+    let n = SchemaNode(kind: snkEmbedded, embed: popStack())
     pushStack n
 
   LiteralPattern <- ('=' * >symbol) | ("<<lit>" * >Preserves.Value * ">") | >nonSymbolAtom: