Drafting a module to share compress grids

js/Share.js

@@ -0,0 +1,78 @@
+return {
+	compress: compress,
+	naive: naive
+}
+
+function compress(grid) {
+	var state = {
+		data: '',
+		stack: 0,
+		size: 0
+	};
+	var color;
+	var count;
+	for(var i = 0; i < grid.length; i++) {
+		for(var j = 0; j < grid.length; j++) {
+			if(color == undefined) {
+				color = grid[i][j];
+			} else if(grid[i][j] != color) {
+			} else if(count > 6) {
+			} else {
+				count++;
+			}
+		}
+	}
+	return atob(compressed);
+}
+
+function appendLength(state, n) {
+	append(state, 1);
+	for(var i = 0; i < 3; i++) {
+		append(state, n % 2);
+		n >>= 1;
+	}
+}
+
+function appendColor(state, c) {
+	append(state, 0);
+	for(var i = 0; i < 3; i++) {
+		append(state, c % 2);
+		c >>= 1;
+	}
+}
+
+function appendColorNaive(state, c) {
+	for(var i = 0; i < 3; i++) {
+		append(state, c % 2);
+		c >>= 1;
+	}
+}
+
+function append(state, one) {
+	if(state.size > 7) {
+		flush(state);
+	}
+	state.stack = 2*state.stack + (one ? 1 : 0);
+	state.size++;
+}
+
+function flush(state) {
+	state.data = state.data + String.fromCharCode(state.stack);
+	state.stack = 0;
+	state.size = 0;
+}
+
+function naive(grid) {
+	var state = {
+		data: '',
+		stack: 0,
+		size: 0
+	};
+	for(var i = 0; i < grid.length; i++) {
+		for(var j = 0; j < grid.length; j++) {
+			appendColorNaive(state, grid[i][j]);
+		}
+	}
+	flush(state);
+	return btoa(state.data);
+}