add delimited many

Author: samisuteria

Sources/GraphQL/Language/Lexer.swift

@@ -46,6 +46,22 @@ func advanceLexer(lexer: Lexer) throws -> Token {
     return token
 }
 
+/**
+  * Returns a non-empty list of parse nodes, determined by the parseFn.
+  * This list may begin with a lex token of delimiterKind followed by items separated by lex tokens of tokenKind.
+  * Advances the parser to the next lex token after last item in the list.
+  */
+func delimitedMany<T>(lexer: Lexer, kind: Token.Kind, parseFn: (Lexer) throws -> T) throws -> [T] {
+    _ = try expectOptional(lexer: lexer, kind: kind)
+
+    var nodes: [T] = []
+    repeat {
+        try nodes.append(parseFn(lexer))
+    } while (try expectOptional(lexer: lexer, kind: kind) != nil)
+
+    return nodes
+}
+
 /**
  * The return type of createLexer.
  */