Major directive refactor (#195)

Fixes #188 #144 #76: major refactor of directive parsing, rendering, styling

common/markdown_parser/query.grammar

@@ -0,0 +1,68 @@
+@precedence { logic @left }
+@top Program { Query }
+@skip { space }
+
+Query {
+    Name ( WhereClause | LimitClause | OrderClause | SelectClause | RenderClause )*
+}
+
+commaSep<content> { content ("," content)* }
+
+WhereClause { Where LogicalExpr }
+LimitClause { Limit Number }
+OrderClause { Order Name OrderDirection? }
+SelectClause { Select commaSep<Name> }
+RenderClause { Render (PageRef | String) }
+
+OrderDirection {
+  "desc" | "asc"
+}
+
+Value { Number | String | Bool | Regex | Null | List }
+
+LogicalExpr { FilterExpr (And FilterExpr)* }
+
+FilterExpr {
+  Name "<" Value
+| Name "<=" Value
+| Name "=" Value
+| Name "!=" Value
+| Name ">=" Value
+| Name ">" Value
+| Name "=~" Value
+| Name "!=~" Value
+| Name "in" Value
+}
+
+List { "[" commaSep<Value> "]" }
+
+
+Bool {
+  "true" | "false"
+}
+
+
+@tokens {
+  space { std.whitespace+ }
+  Name { (std.asciiLetter | "-" | "_")+ }
+
+  Where { "where" }
+  Order { "order by" }
+  Select { "select" }
+  Render { "render" }
+  Limit { "limit" }
+  And { "and" }
+  Null { "null" }
+
+  String {
+    ("\"" | "“" | "”") ![\"”“]* ("\"" | "“" | "”")
+  }
+  PageRef {
+    "[" "[" ![\]]* "]" "]"
+  }
+  Regex { "/" ( ![/\\\n\r] | "\\" _ )* "/"? }
+
+  Number { std.digit+ }
+
+  // @precedence { Where, Sort, Select, Render, Limit, And, Null, Name }
+}