grammar.rst

E-HowNet Grammar

This section describes the grammar of the E-HowNet expression.

Text

• TEXT

  • Any non empty string containing the following characters:

    • Alphabets and Numbers (A-Za-z0-9)
    • Unicode Characters (\x80-\U0010FFFF)
    • |, +, -, ., ?, #.

• NUMBER

  • e.g. 1, 0.1, 1e-4

• COINDEX

  • x, x1, x2, ...
  • x? (refer to the not mentioned subject)

Node

Entity

• ~ehn.parse.node.entity.EhnParseNormalEntity

  • {TEXT}
  • {TEXT:FEATURE}
  • {TEXT:FEATURE,FEATURE}
  • {TEXT:FEATURE,FEATURE,...}
  • {TEXT_COINDEX:FEATURE}
  • {TEXT_COINDEX:FEATURE,FEATURE}
  • {TEXT_COINDEX:FEATURE,FEATURE,...}

• ~ehn.parse.node.entity.EhnParseFunctionEntity

  • {FUNCTION}
  • {FUNCTION:FEATURE}
  • {FUNCTION:FEATURE,FEATURE}
  • {FUNCTION:FEATURE,FEATURE,...}
  • {FUNCTION_COINDEX:FEATURE}
  • {FUNCTION_COINDEX:FEATURE,FEATURE}
  • {FUNCTION_COINDEX:FEATURE,FEATURE,...}

• ~ehn.parse.node.entity.EhnParseAnyEntity

  {}

• ~ehn.parse.node.entity.EhnParseNameEntity

  {"TEXT"}

• ~ehn.parse.node.entity.EhnParseNumberEntity

  {NUMBER}

• ~ehn.parse.node.entity.EhnParseTildeEntity

  {~}

  0.6

• ~ehn.parse.node.entity.EhnParseCoindexEntity

  {COINDEX}

Feature

• ~ehn.parse.node.feature.EhnParseNormalFeature

  • TEXT=ENTITY
  • TEXT=RESTRICTION

• ~ehn.parse.node.feature.EhnParseFunctionFeature

  • FUNCTION=ENTITY
  • FUNCTION=RESTRICTION

Function

• ~ehn.parse.node.other.EhnParseFunction

  • TEXT()
  • TEXT(RESTRICTION)
  • TEXT(ENTITY)
  • TEXT(ENTITY,ENTITY)
  • TEXT(ENTITY,ENTITY,...)

Restriction

• ~ehn.parse.node.other.EhnParseRestriction

  • /ENTITY
  • /ENTITY_COINDEX

Valid Expressions

ENTITY or any number of FEATUREs joined by ,s.

• ENTITY
• FEATURE
• FEATURE,FEATURE
• FEATURE,FEATURE,...