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

• EhnParseNormalEntity

  • {TEXT}

  • {TEXT:FEATURE}

  • {TEXT:FEATURE,FEATURE}

  • {TEXT:FEATURE,FEATURE,...}

  • {TEXT_COINDEX:FEATURE}

  • {TEXT_COINDEX:FEATURE,FEATURE}

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

• EhnParseFunctionEntity

  • {FUNCTION}

  • {FUNCTION:FEATURE}

  • {FUNCTION:FEATURE,FEATURE}

  • {FUNCTION:FEATURE,FEATURE,...}

  • {FUNCTION_COINDEX:FEATURE}

  • {FUNCTION_COINDEX:FEATURE,FEATURE}

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

• EhnParseAnyEntity

  {}

• EhnParseNameEntity

  {"TEXT"}

• EhnParseNumberEntity

  {NUMBER}

• EhnParseTildeEntity

  {~}

  Deprecated since version 0.6.

• EhnParseCoindexEntity

  {COINDEX}

Feature

• EhnParseNormalFeature

  • TEXT=ENTITY

  • TEXT=RESTRICTION

• EhnParseFunctionFeature

  • FUNCTION=ENTITY

  • FUNCTION=RESTRICTION

Function

• EhnParseFunction

  • TEXT()

  • TEXT(RESTRICTION)

  • TEXT(ENTITY)

  • TEXT(ENTITY,ENTITY)

  • TEXT(ENTITY,ENTITY,...)

Restriction

• EhnParseRestriction

  • /ENTITY

  • /ENTITY_COINDEX

Valid Expressions

ENTITY or any number of FEATUREs joined by ,s.

• ENTITY

• FEATURE

• FEATURE,FEATURE

• FEATURE,FEATURE,...