coaparam.js
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'use strict';
const fs = require('fs');
const CoaObject = require('./coaobject');
/**
* COA Parameter
*
* Base class for options and arguments
*
* --------|-----|-----|-----
* | Cmd | Opt | Arg
* --------|-----|-----|-----
* arr | | ✓ | ✓
* req | | ✓ | ✓
* val | | ✓ | ✓
* def | | ✓ | ✓
* input | | ✓ | ✓
* output | | ✓ | ✓
*
* @class CoaParam
* @extends CoaObject
*/
module.exports = class CoaParam extends CoaObject {
constructor(cmd) {
super(cmd);
this._arr = false;
this._req = false;
this._val = undefined;
this._def = undefined;
}
/**
* Makes a param accepts multiple values.
* Otherwise, the value will be used by the latter passed.
*
* @returns {COA.CoaParam} - this instance (for chainability)
*/
arr() {
this._arr = true;
return this;
}
/**
* Makes a param required.
*
* @returns {COA.CoaParam} - this instance (for chainability)
*/
req() {
this._req = true;
return this;
}
/**
* Set a validation (or value) function for param.
* Value from command line passes through before becoming available from API.
* Using for validation and convertion simple types to any values.
*
* @param {Function} val - validating function,
* invoked in the context of option instance
* and has one parameter with value from command line.
* @returns {COA.CoaParam} - this instance (for chainability)
*/
val(val) {
this._val = val;
return this;
}
/**
* Set a default value for param.
* Default value passed through validation function as ordinary value.
*
* @param {*} def - default value of function generator
* @returns {COA.CoaParam} - this instance (for chainability)
*/
def(def) {
this._def = def;
return this;
}
/**
* Make option value inputting stream.
* It's add useful validation and shortcut for STDIN.
*
* @returns {COA.CoaParam} - this instance (for chainability)
*/
input() {
process.stdin.pause();
return this
.def(process.stdin)
.val(function(v) {
if(typeof v !== 'string')
return v;
if(v === '-')
return process.stdin;
const s = fs.createReadStream(v, { encoding : 'utf8' });
s.pause();
return s;
});
}
/**
* Make option value outputing stream.
* It's add useful validation and shortcut for STDOUT.
*
* @returns {COA.CoaParam} - this instance (for chainability)
*/
output() {
return this
.def(process.stdout)
.val(function(v) {
if(typeof v !== 'string')
return v;
if(v === '-')
return process.stdout;
return fs.createWriteStream(v, { encoding : 'utf8' });
});
}
};