support conditional prompts

Author: yyx990803

lib/ask.js

@@ -1,5 +1,6 @@
 var async = require('async')
 var inquirer = require('inquirer')
+var evaluate = require('./eval')
 
 // Support types from prompt-for which was used before
 var promptMapping = {
@@ -31,6 +32,10 @@ module.exports = function ask (schema, data, done) {
  */
 
 function prompt (data, key, prompt, done) {
+  // skip prompts whose when condition is not met
+  if (prompt.when && !evaluate(prompt.when, data)) {
+    return done()
+  }
   inquirer.prompt([{
     type: promptMapping[prompt.type] || prompt.type,
     name: key,

lib/eval.js

@@ -0,0 +1,14 @@
+/**
+ * Evaluate an expression in meta.json in the context of
+ * prompt answers data.
+ */
+
+module.exports = function evalualte (exp, data) {
+  /* eslint-disable no-new-func */
+  var fn = new Function('data', 'with (data) { return ' + exp + '}')
+  try {
+    return fn(data)
+  } catch (e) {
+    console.error(chalk.red('Error when evaluating filter condition: ' + exp))
+  }
+}

lib/filter.js

@@ -1,5 +1,6 @@
 var match = require('minimatch')
 var chalk = require('chalk')
+var evaluate = require('./eval')
 
 module.exports = function (files, filters, data, done) {
   if (!filters) {
@@ -10,21 +11,11 @@ module.exports = function (files, filters, data, done) {
     fileNames.forEach(function (file) {
       if (match(file, glob)) {
         var condition = filters[glob]
-        if (!evalualte(condition, data)) {
+        if (!evaluate(condition, data)) {
           delete files[file]
         }
       }
     })
   })
   done()
 }
-
-function evalualte (exp, data) {
-  /* eslint-disable no-new-func */
-  var fn = new Function('data', 'with (data) { return ' + exp + '}')
-  try {
-    return fn(data)
-  } catch (e) {
-    console.error(chalk.red('Error when evaluating filter condition: ' + exp))
-  }
-}