[ios, macos] Insert example code in original headers (#7569)

* [ios, macos] Removed extraneous code fences

* [ios] Streamlined example delimiters

Use test method names as names of example blocks and test method documentation comments as front matter for examples. Set off example blocks using a syntax similar to playground markup syntax. Avoid hard-coding indentation levels. Trigger Xcode build error when an error occurs in the script.

* [ios] Removed platform-specific code from examples

* [ios] Fixed logic error

The comment said 200 while the code said 1,500.

* [ios] Formalize build phase input

* [ios] Insert examples into original source documentation

Rewrote the example code insertion script to work on the original source files and overwrite any existing code examples on the same symbols. The script uses SourceKitten to find the documentation comment for the symbol named by the test method.

Replaced the Run Script build phase that runs the example code insertion script with a make rule that runs the same script. Inlined skeleton examples minus the contents of the code blocks.

* [ios] Fixed syntax error

* [ios] Ran ios-add-examples-to-docs

* [ios] Avoid touching unchanged headers

* [ios] Refactored example insertion script

* [ios] Point jazzy at original sources

* [ios] Invoke SourceKitten only once

* [ios] Look for methods as well as properties

* [ios] Thoroughly search for code blocks in doc comments

Refactored the example code insertion script to index test methods by their names, then recursively search the SourceKitten output for documentation comments that contain Swift code blocks, replacing each code block with the associated test method body.

* [ios, macos] Enabled example insertion for macOS

The example code insertion script is now platform-agnostic.

* [ios, macos] Fixed documentation example tests

Set the map view’s style to a minimal local JSON file. Wait for the style to finish loading before running each test. Corrected CGVector type.

* [ios, macos] Dry run mode

The output of this mode isn’t a good indicator of whether any files would’ve needed to be changed, because the presence of a conditional compilation block in one of the test methods means this script would always change and revert the corresponding comment.

* [ios] Fixed test failure

The iOS implementation of MGLMapView tries to show the Streets style by default even if no access token has been set. Avoid a race condition and frequent test failure by specifying the minimal style on initialization.

* [ios, macos] Ensure SourceKitten is installed before inserting example code

* [ios, macos] Tear down map view after each test

Keep map views from previous tests from hanging around, potentially obscuring the result of a subsequent test. Set the access token to a bogus token upfront for all style layer tests. Unified MGLStyle usage within MGLStyleTests.

* [ios, macos] Reinsert examples after generating runtime styling headers

1 files changed, 152 insertions, 0 deletions

diff --git a/platform/darwin/scripts/update-examples.js b/platform/darwin/scripts/update-examples.js
new file mode 100644
index 0000000000..2aeb80e139
--- /dev/null
+++ b/platform/darwin/scripts/update-examples.js
@@ -0,0 +1,152 @@
+'use strict';
+
+const fs = require('fs');
+const execFileSync = require('child_process').execFileSync;
+const _ = require('lodash');
+
+const examplesSrc = fs.readFileSync('platform/darwin/test/MGLDocumentationExampleTests.swift', 'utf8');
+
+// Regex extracts the following block
+// /** Front matter to describe the example. **/
+// func testMGLClass$member() {
+//     ...
+//     //#-example-code
+//     let sampleCode: String?
+//     //#-end-example-code
+//     ...
+// }
+//
+// into the following regex groups:
+// 1 (test method name): "MGLClass" or "MGLClass$member" or "MGLClass$initWithArg_anotherArg_"
+// 2 (indentation): "    "
+// 3 (sample code): "let sampleCode: String?"
+const exampleRegex = /func test([\w$]+)\s*\(\)\s*\{[^]*?\n([ \t]+)\/\/#-example-code\n([^]+?)\n\2\/\/#-end-example-code\n/gm;
+
+/**
+ * Returns the given source with example code inserted into the documentation
+ * comment for the symbol at the given one-based line.
+ *
+ * @param {String} src Source code to insert the example code into.
+ * @param {Number} line One-based line number of the symbol being documented.
+ * @param {String} exampleCode Example code to insert.
+ * @returns {String} `src` with `exampleCode` inserted just above `line`.
+ */
+function completeSymbolInSource(src, line, exampleCode) {
+  // Split the file contents right before the symbol declaration (but after its documentation comment).
+  let srcUpToSymbol = src.split('\n', line - 1).join('\n');
+  let srcFromSymbol = src.substr(srcUpToSymbol.length);
+  
+  // Match the documentation comment block that is not followed by the beginning or end of a declaration.
+  let commentMatch = srcUpToSymbol.match(/\/\*\*\s*(?:[^*]|\*(?!\/))+?\s*\*\/[^;{}]*?$/);
+  
+  // Replace the Swift code block with the test method’s contents.
+  let completedComment = commentMatch[0].replace(/^([ \t]*)```swift\n[^]*?```/m, function (m, indentation) {
+    // Apply the original indentation to each line.
+    return ('```swift\n' + exampleCode + '\n```').replace(/^/gm, indentation);
+  });
+  
+  // Splice the modified comment into the overall file contents.
+  srcUpToSymbol = (srcUpToSymbol.substr(0, commentMatch.index) + completedComment +
+                   srcUpToSymbol.substr(commentMatch.index + commentMatch[0].length));
+  return srcUpToSymbol + srcFromSymbol;
+}
+
+let examples = {};
+let match;
+while ((match = exampleRegex.exec(examplesSrc)) !== null) {
+  let testMethodName = match[1],
+      indentation = match[2],
+      exampleCode = match[3];
+
+  // Trim leading whitespace from the example code.
+  exampleCode = exampleCode.replace(new RegExp('^' + indentation, 'gm'), '');
+  
+  examples[testMethodName] = exampleCode;
+}
+
+function completeExamples(os) {
+  console.log(`Installing ${os} SDK examples…`);
+  
+  let sdk = os === 'iOS' ? 'iphonesimulator' : 'macosx';
+  let sysroot = execFileSync('xcrun', ['--show-sdk-path', '--sdk', sdk]).toString().trim();
+  let umbrellaPath = `platform/${os.toLowerCase()}/src/Mapbox.h`;
+  let docArgs = ['doc', '--objc', umbrellaPath, '--',
+                 '-x', 'objective-c', '-I', 'platform/darwin/src/', '-isysroot', sysroot];
+  let docStr = execFileSync('sourcekitten', docArgs).toString().trim();
+  let docJson = JSON.parse(docStr);
+  _.forEach(docJson, function (result) {
+    _.forEach(result, function (structure, path) {
+      let src;
+      let newSrc;
+      // Recursively search for code blocks in documentation comments and populate
+      // them with example code from the test methods. Find and replace the code
+      // blocks in reverse to keep the SourceKitten line numbers accurate.
+      _.forEachRight(structure['key.substructure'], function completeSubstructure(substructure, idx, substructures, symbolPath) {
+        if (!symbolPath) {
+          symbolPath = [substructure['key.name']];
+        }
+        _.forEachRight(substructure['key.substructure'], function (substructure, idx, substructures) {
+          completeSubstructure(substructure, idx, substructures, _.concat(symbolPath, substructure['key.name']));
+        });
+        
+        let comment = substructure['key.doc.comment'];
+        if (!comment || !comment.match(/^(?:\s*)```swift\n/m)) {
+          return;
+        }
+        
+        // Lazily read in the existing file.
+        if (!src) {
+          newSrc = src = fs.readFileSync(path, 'utf8');
+        }
+        
+        // Get the contents of the test method whose name matches the symbol path.
+        let testMethodName = symbolPath.join('$').replace(/$[+-]/, '').replace(/:/g, '_');
+        let example = examples[testMethodName];
+        if (!example) {
+          console.error(`MGLDocumentationExampleTests.${testMethodName}() not found.`);
+          process.exit(1);
+        }
+        
+        // Resolve conditional compilation blocks.
+        example = example.replace(/^(\s*)#if\s+os\((iOS|macOS)\)\n([^]*?)(?:^\1#else\n([^]*?))?^\1#endif\n/gm,
+                                  function (m, indentation, ifOs, ifCase, elseCase) {
+          return (os === ifOs ? ifCase : elseCase).replace(new RegExp('^    ', 'gm'), '');
+        });
+        
+        // Insert the test method contents into the documentation comment just
+        // above the substructure.
+        let startLine = substructure['key.parsed_scope.start'];
+        newSrc = completeSymbolInSource(newSrc, startLine, example);
+      });
+      
+      if (!src) {
+        return;
+      }
+      
+      // Write out the modified file contents.
+      if (src === newSrc) {
+        console.log('Skipping', path);
+      } else {
+        console.log('Updating', path);
+        if (['0', 'false'].indexOf(process.env.DRY_RUN || '0') !== -1) {
+          fs.writeFileSync(path, newSrc);
+        }
+      }
+    });
+  });
+}
+
+function ensureSourceKittenIsInstalled() {
+  try {
+    execFileSync('which', ['sourcekitten']);
+  } catch (e) {
+    console.log(`Installing SourceKitten via Homebrew…`);
+    execFileSync('brew', ['install', 'sourcekitten']);
+  }
+}
+
+ensureSourceKittenIsInstalled();
+
+// Where a particular comment is part of both SDKs, prefer the iOS example.
+completeExamples('macOS');
+completeExamples('iOS');