// CodeMirror, copyright (c) by Marijn Haverbeke and others
// Distributed under an MIT license: https://codemirror.net/LICENSE

// codemirror: v.5.61.1

// Utility function that allows modes to be combined. The mode given
// as the base argument takes care of most of the normal mode
// functionality, but a second (typically simple) mode is used, which
// can override the style of text. Both modes get to parse all of the
// text, but when both assign a non-null style to a piece of code, the
// overlay wins, unless the combine argument was true and not overridden,
// or state.overlay.combineTokens was true, in which case the styles are
// combined.

(function(mod) {
	if (typeof exports == "object" && typeof module == "object") // CommonJS
		mod(require("../../lib/codemirror"));
	else if (typeof define == "function" && define.amd) // AMD
		define(["../../lib/codemirror"], mod);
	else // Plain browser env
		mod(CodeMirror);
})(function(CodeMirror) {
"use strict";

CodeMirror.overlayMode = function(base, overlay, combine) {
	return {
		startState: function() {
			return {
				base: CodeMirror.startState(base),
				overlay: CodeMirror.startState(overlay),
				basePos: 0, baseCur: null,
				overlayPos: 0, overlayCur: null,
				streamSeen: null
			};
		},
		copyState: function(state) {
			return {
				base: CodeMirror.copyState(base, state.base),
				overlay: CodeMirror.copyState(overlay, state.overlay),
				basePos: state.basePos, baseCur: null,
				overlayPos: state.overlayPos, overlayCur: null
			};
		},

		token: function(stream, state) {
			if (stream != state.streamSeen ||
					Math.min(state.basePos, state.overlayPos) < stream.start) {
				state.streamSeen = stream;
				state.basePos = state.overlayPos = stream.start;
			}

			if (stream.start == state.basePos) {
				state.baseCur = base.token(stream, state.base);
				state.basePos = stream.pos;
			}
			if (stream.start == state.overlayPos) {
				stream.pos = stream.start;
				state.overlayCur = overlay.token(stream, state.overlay);
				state.overlayPos = stream.pos;
			}
			stream.pos = Math.min(state.basePos, state.overlayPos);

			// state.overlay.combineTokens always takes precedence over combine,
			// unless set to null
			if (state.overlayCur == null) return state.baseCur;
			else if (state.baseCur != null &&
							 state.overlay.combineTokens ||
							 combine && state.overlay.combineTokens == null)
				return state.baseCur + " " + state.overlayCur;
			else return state.overlayCur;
		},

		indent: base.indent && function(state, textAfter, line) {
			return base.indent(state.base, textAfter, line);
		},
		electricChars: base.electricChars,

		innerMode: function(state) { return {state: state.base, mode: base}; },

		blankLine: function(state) {
			var baseToken, overlayToken;
			if (base.blankLine) baseToken = base.blankLine(state.base);
			if (overlay.blankLine) overlayToken = overlay.blankLine(state.overlay);

			return overlayToken == null ?
				baseToken :
				(combine && baseToken != null ? baseToken + " " + overlayToken : overlayToken);
		}
	};
};

});

// #END
