RELAX NG compact syntax cheat sheet

cheatsheet.rnc

# RELAX NG compact syntax cheat sheet

# See also:
# * tutorial <http://www.relaxng.org/compact-tutorial-20030326.html>
# * spec <http://www.relaxng.org/compact-20021121.html>

# Checking a XML file:
#
#     jing -c schema.rnc file.xml
#
# Converting the compact syntax to the regular (XML) syntax:
#
#     trang -i rnc -o rng schema.rnc schema.rng

# For a simple schema, the top-level can contain the root element definition
element root {
  # mandatory attribute
  attribute foo { text },

  # optional attribute
  attribute bar { text }?,

  # nested elements
  element nested { element even_more_nested { empty } },

  # empty elements (<empty/>)
  element empty { empty },

  # elements containing text (<tag>whatever</tag>)
  element tag { text },

  # choice (either <a/> or <b/>)
  (element a { empty } | element b { empty }),

  # if the order of the elements does not matter, use "&" instead of ","
  # (this matches <a/><b/> as well as <b/><a/>)
  element container {
    element a { empty } &
    element b { empty } 
  },

  # text mixed with elements (foo<a/>bar)
  element container2 {
    # this is the same as "text & element a { empty }"
    mixed { element a { empty } }
  },

  # quantifiers:
  # ?: zero or one occurence (item is optional)
  # *: zero or more occurences
  # +: one or more occurences
  element q1 { text }?,
  element q2 { text }*,
  element q3 { text }+

  # * matches any name
  element wildcards {
    attribute * { text },
    element * { empty }
  }
}

# For complex schemata, use grammar { }
grammar { 
  # start defines the root element
  start = element root {
    # elements can refer to other definitions
    recursive-a*
  }

  # the definitions can be recursive (e.g. <a><a><a/></a></a>)
  recursive-a = (element a { recursive-a } | empty)
}

# Not covered by this cheatsheet: datatypes, lists, annotations, namespaces,
# external patterns, nameclass connectors, etc. See the spec and the tutorial!