QML - Programming language

QML, aka Qt Modeling Language, is a programming language created in 2009.

#227on PLDB

15Years Old

15kRepos

QML (Qt Modeling Language) is a user interface markup language. It is a declarative language (similar to CSS and JSON) for designing user interface–centric applications. Inline JavaScript code handles imperative aspects. Read more on Wikipedia...

Tags: programming language
There are at least 14,755 QML repos on GitHub
Early development of QML happened in Qt Group plc
The Google BigQuery Public Dataset GitHub snapshot shows 4k users using QML in 5k repos on GitHub
Pygments supports syntax highlighting for QML
GitHub supports syntax highlighting for QML
See also: (3 related languages) JSON, JavaScript, Ring
7 PLDB concepts link to QML: Ace Editor, kumir, leo-editor, Opa, Pygments, score, VLC

Example from the web:

Item {
    Rectangle {
        id: myRect
        width: 120
        height: 100
    }
    Rectangle {
        width: myRect.width
        height: 200
    }
}

Example from Linguist:

/****************************************************************************
**
** Copyright (C) 2015 The Qt Company Ltd.
** Contact: http://www.qt.io/licensing
**
** This file is part of the Qt Build Suite.
**
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms and
** conditions see http://www.qt.io/terms-conditions. For further information
** use the contact form at http://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 or version 3 as published by the Free
** Software Foundation and appearing in the file LICENSE.LGPLv21 and
** LICENSE.LGPLv3 included in the packaging of this file.  Please review the
** following information to ensure the GNU Lesser General Public License
** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, The Qt Company gives you certain additional
** rights.  These rights are described in The Qt Company LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
****************************************************************************/

import qbs 1.0
import qbs.FileInfo
import qbs.ModUtils

Module {
    property string buildVariant: "debug"
    property bool enableDebugCode: buildVariant == "debug"
    property bool debugInformation: (buildVariant == "debug")
    property string optimization: (buildVariant == "debug" ? "none" : "fast")
    readonly property stringList hostOS: undefined // set internally
    property string hostOSVersion: {
        if (hostOS && hostOS.contains("osx")) {
            return getNativeSetting("/System/Library/CoreServices/ServerVersion.plist", "ProductVersion") ||
                   getNativeSetting("/System/Library/CoreServices/SystemVersion.plist", "ProductVersion");
        } else if (hostOS && hostOS.contains("windows")) {
            var version = getNativeSetting("HKEY_LOCAL_MACHINE\\Software\\Microsoft\\Windows NT\\CurrentVersion", "CurrentVersion");
            return version + "." + hostOSBuildVersion;
        }
    }

    property string hostOSBuildVersion: {
        if (hostOS.contains("osx")) {
            return getNativeSetting("/System/Library/CoreServices/ServerVersion.plist", "ProductBuildVersion") ||
                   getNativeSetting("/System/Library/CoreServices/SystemVersion.plist", "ProductBuildVersion");
        } else if (hostOS.contains("windows")) {
            return getNativeSetting("HKEY_LOCAL_MACHINE\\Software\\Microsoft\\Windows NT\\CurrentVersion", "CurrentBuildNumber");
        }
    }

    readonly property var hostOSVersionParts: hostOSVersion ? hostOSVersion.split('.').map(function(item) { return parseInt(item, 10); }) : []
    readonly property int hostOSVersionMajor: hostOSVersionParts[0] || 0
    readonly property int hostOSVersionMinor: hostOSVersionParts[1] || 0
    readonly property int hostOSVersionPatch: hostOSVersionParts[2] || 0

    property stringList targetOS: hostOS
    property string pathListSeparator: hostOS.contains("windows") ? ";" : ":"
    property string pathSeparator: hostOS.contains("windows") ? "\\" : "/"
    property string profile
    property stringList toolchain
    property string architecture
    property bool install: false
    property string installSourceBase
    readonly property string installRoot: undefined
    property string installDir
    property string installPrefix: ""
    property path sysroot

    PropertyOptions {
        name: "buildVariant"
        allowedValues: ['debug', 'release']
        description: "name of the build variant"
    }

    PropertyOptions {
        name: "optimization"
        allowedValues: ['none', 'fast', 'small']
        description: "optimization level"
    }

    validate: {
        var validator = new ModUtils.PropertyValidator("qbs");
        validator.setRequiredProperty("architecture", architecture,
                                      "you might want to re-run 'qbs-setup-toolchains'");
        validator.setRequiredProperty("hostOS", hostOS);
        validator.setRequiredProperty("targetOS", targetOS);
        if (hostOS && (hostOS.contains("windows") || hostOS.contains("osx"))) {
            validator.setRequiredProperty("hostOSVersion", hostOSVersion,
                                          "could not detect host operating system version; " +
                                          "verify that system files and registry keys have not " +
                                          "been modified.");
            if (hostOSVersion)
                validator.addVersionValidator("hostOSVersion", hostOSVersion, 2, 4);

            validator.setRequiredProperty("hostOSBuildVersion", hostOSBuildVersion,
                                          "could not detect host operating system build version; " +
                                          "verify that system files or registry have not been " +
                                          "tampered with.");
        }

        validator.addCustomValidator("architecture", architecture, function (value) {
            return architecture === canonicalArchitecture(architecture);
        }, "'" + architecture + "' is invalid. You must use the canonical name '" +
        canonicalArchitecture(architecture) + "'");

        validator.validate();
    }

    // private properties
    property var commonRunEnvironment: {
        var env = {};
        if (targetOS.contains("windows")) {
            env["PATH"] = [
                FileInfo.joinPaths(installRoot, installPrefix)
            ];
        } else if (hostOS.contains("darwin") && targetOS.contains("darwin")) {
            env["DYLD_FRAMEWORK_PATH"] = [
                FileInfo.joinPaths(installRoot, installPrefix, "Library", "Frameworks"),
                FileInfo.joinPaths(installRoot, installPrefix, "lib"),
                FileInfo.joinPaths(installRoot, installPrefix)
            ].join(pathListSeparator);

            env["DYLD_LIBRARY_PATH"] = [
                FileInfo.joinPaths(installRoot, installPrefix, "lib"),
                FileInfo.joinPaths(installRoot, installPrefix, "Library", "Frameworks"),
                FileInfo.joinPaths(installRoot, installPrefix)
            ].join(pathListSeparator);

            if (targetOS.contains("ios-simulator") && sysroot) {
                env["DYLD_ROOT_PATH"] = [sysroot];
            }
        } else if (hostOS.contains("unix") && targetOS.contains("unix")) {
            env["LD_LIBRARY_PATH"] = [
                FileInfo.joinPaths(installRoot, installPrefix, "lib")
            ];
        }

        return env;
    }

    // internal properties
    readonly property string version: [versionMajor, versionMinor, versionPatch].join(".")
    readonly property int versionMajor: undefined // set internally
    readonly property int versionMinor: undefined // set internally
    readonly property int versionPatch: undefined // set internally
}

Example from Wikipedia:

MouseArea {
     onPressed: console.log("mouse button pressed")
 }

Language features

Feature	Supported	Example	Token
Integers	✓	// [0-9]+
Floats	✓	// [0-9][0-9]*\.[0-9]+([eE][0-9]+)?[fd]?
Hexadecimals	✓	// 0x[0-9a-fA-F]+
MultiLine Comments	✓	/* A comment */	/* */
Comments	✓	// A comment
Line Comments	✓	// A comment	//
Semantic Indentation	X