Webterm
Specs and discussions for the Webterm environment.
Contribute
Webterm is still in development. Open issues and PRs to discuss the design of the shell grammar and environment.
Active proposals:
Current Grammar
The current shell grammar follows the following BNF:
// Webterm Input Grammar (PEG.js)
// ==============================
Expression
= Term+
Term
= term:Switch _? { return {type: 'param', key: term.key, value: term.value} }
/ term:String _? { return {type: 'token', value: term} }
Switch "switch"
= '-'+ key:String _+ value:NonSwitch { return {key, value} }
/ '-'+ key:String { return {key, value: undefined} }
NonSwitch "non-switch"
= !'-' value:String { return value }
String "string"
= head:Char rest:CharOrQuote* { return head + rest.join('') }
/ '"' value:CharOr_OrSingleQuote* '"' { return value.join('') }
/ '\'' value:CharOr_OrDoubleQuote* '\'' { return value.join('') }
CharOr_OrDoubleQuote "character, whitespace, or double quote"
= CharOr_
/ '"'
CharOr_OrSingleQuote "character, whitespace, or single quote"
= CharOr_
/ '\''
CharOr_ "character or whitespace"
= Char
/ _
CharOrQuote "character, single quote, or double quote"
= Char
/ '\''
/ '"'
Char "character"
= '\\ ' { return ' ' } // escaped space
/ [^ "'\f\n\r\t\v\u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff]i // regular characters
_ "whitespace"
= [ \t]+
Current Execution Model
Every shell-input translates to a call of a single javascript function, called a "shell command function."
Every command function is expected to match the following signature:
function cmdname (opts:Object, ...args:any): Promise<any>
The opts argument is an object which contains all switch inputs (short-switch and long-switch). The remaining args are an ordered list of the argument inputs.
If the function's resolved value possesses a toHTML() function, that function will be called during the result rendering and its value will be used in the shell output.