Initial commit

.eslintrc

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+{
+	"extends": "@joepie91/eslint-config"
+}

.gitignore

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+node_modules

index.js

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+"use strict";
+
+const Promise = require("bluebird");
+
+const { validateArguments } = require("@validatem/core");
+const required = require("@validatem/required");
+const isFunction = require("@validatem/is-function");
+const propagateAbort = require("@promistream/propagate-abort");
+const propagatePeek = require("@promistream/propagate-peek");
+
+module.exports = function mapFilter(_predicate) {
+	let [ predicate ] = validateArguments(arguments, {
+		predicate: [ required, isFunction ]
+	});
+
+	return {
+		_promistreamVersion: 0,
+		description: `map-filter stream`,
+		abort: propagateAbort,
+		peek: propagatePeek,
+		read: function produceValue_mapFilterStream(source) {
+			function attemptRead() {
+				return Promise.try(() => {
+					return source.read();
+				}).then((result) => {
+					return Promise.try(() => {
+						return predicate(result);
+					}).then((mappedItem) => {
+						if (mappedItem === module.exports.NoValue) {
+							return attemptRead();
+						} else {
+							return mappedItem;
+						}
+					});
+				});
+			}
+
+			return attemptRead();
+		}
+	};
+};
+
+module.exports.NoValue = Symbol("NoValue");

package.json

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+{
+  "name": "@promistream/map-filter",
+  "description": "A Promistream that's optimized for the 'map some items and throw away the rest' usecase",
+  "version": "0.1.0",
+  "main": "index.js",
+  "keywords": [
+    "promistream"
+  ],
+  "repository": "http://git.cryto.net/joepie91/map-filter.git",
+  "author": "Sven Slootweg <admin@cryto.net>",
+  "license": "WTFPL OR CC0-1.0",
+  "devDependencies": {
+    "@joepie91/eslint-config": "^1.1.0",
+    "eslint": "^6.8.0"
+  },
+  "dependencies": {
+    "@promistream/propagate-abort": "^0.1.6",
+    "@promistream/propagate-peek": "^0.1.1",
+    "@validatem/core": "^0.3.15",
+    "@validatem/is-function": "^0.1.0",
+    "@validatem/required": "^0.1.1",
+    "bluebird": "^3.7.2"
+  }
+}