Hera - Grammar language

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Hera is a grammar language created in 2021 by Daniel X Moore.

#2209on PLDB

3Years Old

Download source code:

git clone https://github.com/DanielXMoore/Hera

Source Code

Elegant parsing expression grammars

Tags: grammarLanguage
Hera is developed on GitHub and has 47 stars
Hera is written in JSON, TypeScript, JavaScript, Go, CoffeeScript, Markdown, YAML, Bash, Bourne shell, Make

Example from the web:

# WIP Coffee-like lang

Grammar
  Line*

Line
  Indent Content EOL
  Indent EOL

Indent
  "  "*

Content
  Statement
  Expression

Expression
  Applied

# Function application:
# a b
# a(b)
# a b, c, d
# a(b, c, d)
Applied
  Operated Application?

Application
  "()"
  __ "(" ArgumentList ")"
  Space+ ArgumentList

ArgumentList
  Expression (__ "," __ Expression)*

Operated
  Assigned (__ BinaryOp __ Assigned)*
  UnaryOp* Assigned

Assigned
  (Accessed __ "=" __)+ Expression
  Accessed

Accessed
  Primary Access*

Access
  "?"? "." Name
  "?"? "[" Expression "]"

Primary
  "(" Expression ")"
  Function
  Literal
  Name

This
  "this"
  "@"

Function
  Parameters "->"

Literal
  StringValue
  Numeric
  "true"
  "false"
  "null"
  "undefined"

Parameters
  "(" Name (Comma Name)+ ")"
  "(" Name ")"
  ""

Comma
  Space* "," Space*

Name
  [$a-zA-Z_][$a-zA-Z0-9_]*

BinaryOp
  "+"
  "-"
  "*"
  "/"
  "and"
  "&&"
  "or"
  "||"

# TODO: delete, void, typeof
UnaryOp
  [!~+-]

Statement
  Import
  Export

Import
  /import[^\r\n]*/

Export
  /export[^\r\n]*/

Numeric
  /\d+(?:\.\d*)?/

StringValue
  "\"" $DoubleStringCharacter* "\"" -> $2
  "\'" $SingleStringCharacter* "\'" -> $2

DoubleStringCharacter
  [^"\\]+
  EscapeSequence

SingleStringCharacter
  [^'\\]+
  EscapeSequence

EscapeSequence
  $( "\\" . )

# Required non-newline white space
Space
  [\t ]

# Whitespace including newlines
__
  /\s*/

# End of line
EOL
  /\r\n|\n|\r/