fix: add context fo parse

src/flags.ts

@@ -14,7 +14,7 @@ export type IFlagBase<T, I> = {
    * also accept an environment variable as input
    */
   env?: string
-  parse(input: I): T
+  parse(input: I, context: any): T
 }
 
 export type IBooleanFlag<T> = IFlagBase<T, boolean> & {

src/index.ts

@@ -18,7 +18,7 @@ export type ParserInput<TFlags extends flags.Output> = {
 export function parse<TFlags, TArgs extends {[name: string]: string}>(argv: string[], options: ParserInput<TFlags>): ParserOutput<TFlags, TArgs> {
   const input = {
     argv,
-    context,
+    context: options.context,
     args: (options.args || []).map((a: any) => deps.args.newArg(a as any)),
     flags: {
       color: deps.flags.defaultFlags.color,

src/parse.ts

@@ -158,13 +158,13 @@ export class Parser<T extends ParserInput, TFlags extends OutputFlags<T['flags']
         } else {
           flags[token.flag] = true
         }
-        flags[token.flag] = flag.parse(flags[token.flag])
+        flags[token.flag] = flag.parse(flags[token.flag], this.context)
       } else {
         const input = token.input
         if (flag.options && !flag.options.includes(input)) {
           throw new Errors.FlagInvalidOptionError(flag, input)
         }
-        const value = flag.parse ? flag.parse(input) : input
+        const value = flag.parse ? flag.parse(input, this.context) : input
         if (flag.multiple) {
           flags[token.flag] = flags[token.flag] || []
           flags[token.flag].push(value)
@@ -178,7 +178,7 @@ export class Parser<T extends ParserInput, TFlags extends OutputFlags<T['flags']
       if (flags[k] || flag.type !== 'option') continue
       if (flag.env) {
         let input = process.env[flag.env]
-        if (input) flags[k] = flag.parse(input)
+        if (input) flags[k] = flag.parse(input, this.context)
       }
       if (!flags[k] && flag.default) {
         if (typeof flag.default === 'function') {

test/parse.test.ts

@@ -382,4 +382,16 @@ See more help with --help`)
       delete process.env.TEST_FOO
     })
   })
+
+  describe('flag context', () => {
+    it('accepts context in parse', () => {
+      const out = parse(['--foo'], {
+        context: {a: 101},
+        flags: {foo: flags.boolean({
+          parse: (_: any, ctx: any) => ctx.a
+        })},
+      })
+      expect(out.flags.foo).to.equal(101)
+    })
+  })
 })