build(aio): truncate API overview parameters at one line

aio/tools/transforms/angular-base-package/rendering/truncateCode.js

@@ -0,0 +1,49 @@
+module.exports = function() {
+  return {
+    name: 'truncateCode',
+    process: function(str, lines) {
+      if (lines === undefined) return str;
+
+      const parts = str && str.split && str.split(/\r?\n/);
+      if (parts && parts.length > lines) {
+        return balance(parts[0] + '...', ['{', '(', '['], ['}', ')', ']']);
+      } else {
+        return str;
+      }
+    }
+  };
+};
+
+/**
+ * Try to balance the brackets by adding closers on to the end of a string
+ * for every bracket that is left open.
+ * The chars at each index in the openers and closers should match (i.e openers = ['{', '('], closers = ['}', ')'])
+ *
+ * @param {string} str The string to balance
+ * @param {string[]} openers an array of chars that open a bracket
+ * @param {string[]} closers an array of chars that close a brack
+ * @returns the balanced string
+ */
+function balance(str, openers, closers) {
+  const stack = [];
+
+  // Add each open bracket to the stack, removing them when there is a matching closer
+  str.split('').forEach(function(char) {
+    const closerIndex = closers.indexOf(char);
+    if (closerIndex !== -1 && stack[stack.length-1] === closerIndex) {
+      stack.pop();
+    } else {
+      const openerIndex = openers.indexOf(char);
+      if (openerIndex !== -1) {
+        stack.push(openerIndex);
+      }
+    }
+  });
+
+  // Now the stack should contain all the unclosed brackets
+  while(stack.length) {
+    str += closers[stack.pop()];
+  }
+
+  return str;
+}

aio/tools/transforms/angular-base-package/rendering/truncateCode.spec.js

@@ -0,0 +1,35 @@
+var factory = require('./truncateCode');
+
+describe('truncateCode filter', function() {
+  var filter;
+
+  beforeEach(function() { filter = factory(); });
+
+  it('should be called "truncateCode"',
+     function() { expect(filter.name).toEqual('truncateCode'); });
+
+  it('should return the whole string given lines is undefined', function() {
+    expect(filter.process('some text\n  \nmore text\n  \n'))
+      .toEqual('some text\n  \nmore text\n  \n');
+  });
+
+  it('should return the whole string if less than the given number of lines', function() {
+    expect(filter.process('this is a pretty long string that only exists on one line', 1))
+      .toEqual('this is a pretty long string that only exists on one line');
+
+    expect(filter.process('this is a pretty long string\nthat exists on two lines', 2))
+      .toEqual('this is a pretty long string\nthat exists on two lines');
+  });
+
+  it('should return the specified number of lines and an ellipsis if there are more lines', function() {
+    expect(filter.process('some text\n  \nmore text\n  \n', 1)).toEqual('some text...');
+  });
+
+  it('should add closing brackets for all the unclosed opening brackets after truncating', function() {
+    expect(filter.process('()[]{}\nsecond line', 1)).toEqual('()[]{}...');
+    expect(filter.process('([]{}\nsecond line', 1)).toEqual('([]{}...)');
+    expect(filter.process('()[{}\nsecond line', 1)).toEqual('()[{}...]');
+    expect(filter.process('()[]{\nsecond line', 1)).toEqual('()[]{...}');
+    expect(filter.process('([{\nsecond line', 1)).toEqual('([{...}])');
+  });
+});

aio/tools/transforms/angular-base-package/rendering/truncateFirstLine.js

@@ -1,13 +0,0 @@
-module.exports = function() {
-  return {
-    name: 'truncateFirstLine',
-    process: function(str) {
-      const parts = str && str.split && str.split(/\r?\n/);
-      if (parts && parts.length > 1) {
-        return parts[0] + '...';
-      } else {
-        return str;
-      }
-    }
-  };
-};

aio/tools/transforms/angular-base-package/rendering/truncateFirstLine.spec.js

@@ -1,19 +0,0 @@
-var factory = require('./truncateFirstLine');
-
-describe('truncateFirstLine filter', function() {
-  var filter;
-
-  beforeEach(function() { filter = factory(); });
-
-  it('should be called "truncateFirstLine"',
-     function() { expect(filter.name).toEqual('truncateFirstLine'); });
-
-  it('should return the whole string if only one line', function() {
-    expect(filter.process('this is a pretty long string that only exists on one line'))
-      .toEqual('this is a pretty long string that only exists on one line');
-  });
-
-  it('should return the first line and an ellipsis if there is more than one line', function() {
-    expect(filter.process('some text\n  \nmore text\n  \n')).toEqual('some text...');
-  });
-});