Add collapse/expand all under cursor functionality

fx.js

@@ -343,6 +343,24 @@ module.exports = function start(filename, source) {
     }
   })
 
+  // Expand everything under cursor.
+  box.key(['S-right', 'S-l'], function () {
+    hideStatusBar()
+    const [n, line] = getLine(program.y)
+    program.showCursor()
+    program.cursorPos(program.y, line.search(/\S/))
+    const path = index.get(n)
+    const subJson = reduce(json, path)
+    for (let p of dfs(subJson, path)) {
+      if (expanded.size < 1000) {
+        expanded.add(p)
+      } else {
+        break
+      }
+    }
+    render()
+  })
+
   box.key(['left', 'h'], function () {
     hideStatusBar()
     const [n, line] = getLine(program.y)
@@ -380,6 +398,22 @@ module.exports = function start(filename, source) {
     }
   })
 
+  // Collapse all under cursor.
+  box.key(['S-left', 'S-h'], function () {
+    hideStatusBar()
+    const [n, line] = getLine(program.y)
+    program.showCursor()
+    program.cursorPos(program.y, line.search(/\S/))
+    const path = index.get(n)
+    const subJson = reduce(json, path)
+    for (let p of dfs(subJson, path)) {
+      if (expanded.has(p)) {
+        expanded.delete(p)
+      }
+    }
+    render()
+  })
+
   box.on('click', function (mouse) {
     hideStatusBar()
     const [n, line] = getLine(mouse.y)