Use Apache Velocity for templating for generating Build Encyclopedia. Refactor code used for extracting documentation from rule classes into separate class.

Todo after this CL:
* Use RuleDocumentation and RuleDocumentationAttribute directly in .vm templates to further simplify BuildEncyclopediaProcessor code
* Use VTL #include for including common attribute documentation
* Split BE into multiple pages
* Use templating for Skylark Library

--
MOS_MIGRATED_REVID=96865477

1 files changed, 184 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/docgen/BuildDocCollector.java b/src/main/java/com/google/devtools/build/docgen/BuildDocCollector.java
new file mode 100644
index 0000000000..0bf4f20030
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/docgen/BuildDocCollector.java
@@ -0,0 +1,184 @@
+// Copyright 2014 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.docgen;
+
+import com.google.common.collect.LinkedListMultimap;
+import com.google.common.collect.ListMultimap;
+import com.google.devtools.build.docgen.DocgenConsts.RuleType;
+import com.google.devtools.build.lib.analysis.ConfiguredRuleClassProvider;
+import com.google.devtools.build.lib.analysis.RuleDefinition;
+import com.google.devtools.build.lib.packages.Attribute;
+import com.google.devtools.build.lib.packages.RuleClass;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.TreeMap;
+
+/**
+ * Class that parses the documentation fragments of rule-classes and
+ * generates the html format documentation.
+ */
+class BuildDocCollector {
+  private ConfiguredRuleClassProvider ruleClassProvider;
+  private boolean printMessages;
+
+  public BuildDocCollector(ConfiguredRuleClassProvider ruleClassProvider,
+      boolean printMessages) {
+    this.ruleClassProvider = ruleClassProvider;
+    this.printMessages = printMessages;
+  }
+
+  /**
+   * Collects all the rule and attribute documentation present in inputDirs, integrates the
+   * attribute documentation in the rule documentation and returns the rule documentation.
+   */
+  public Map<String, RuleDocumentation> collect(String[] inputDirs)
+      throws BuildEncyclopediaDocException, IOException {
+    // RuleDocumentations are generated in order (based on rule type then alphabetically).
+    // The ordering is also used to determine in which rule doc the common attribute docs are
+    // generated (they are generated at the first appearance).
+    Map<String, RuleDocumentation> ruleDocEntries = new TreeMap<>();
+    // RuleDocumentationAttribute objects equal based on attributeName so they have to be
+    // collected in a List instead of a Set.
+    ListMultimap<String, RuleDocumentationAttribute> attributeDocEntries =
+        LinkedListMultimap.create();
+
+    // Map of rule class name to file that defined it.
+    Map<String, File> ruleClassFiles = new HashMap<>();
+
+    // Set of files already processed. The same file may be encountered multiple times because
+    // directories are processed recursively, and an input directory may be a subdirectory of
+    // another one.
+    Set<File> processedFiles = new HashSet<>();
+
+    for (String inputDir : inputDirs) {
+      if (printMessages) {
+        System.out.println(" Processing input directory: " + inputDir);
+      }
+      int ruleNum = ruleDocEntries.size();
+      collectDocs(processedFiles, ruleClassFiles, ruleDocEntries, attributeDocEntries,
+          new File(inputDir));
+      if (printMessages) {
+        System.out.println(" " + (ruleDocEntries.size() - ruleNum)
+            + " rule documentations found.");
+      }
+    }
+
+    processAttributeDocs(ruleDocEntries.values(), attributeDocEntries);
+    return ruleDocEntries;
+  }
+
+  /**
+   * Go through all attributes of all documented rules and search the best attribute documentation
+   * if exists. The best documentation is the closest documentation in the ancestor graph. E.g. if
+   * java_library.deps documented in $rule and $java_rule then the one in $java_rule is going to
+   * apply since it's a closer ancestor of java_library.
+   */
+  private void processAttributeDocs(Iterable<RuleDocumentation> ruleDocEntries,
+      ListMultimap<String, RuleDocumentationAttribute> attributeDocEntries)
+          throws BuildEncyclopediaDocException {
+    for (RuleDocumentation ruleDoc : ruleDocEntries) {
+      RuleClass ruleClass = ruleClassProvider.getRuleClassMap().get(ruleDoc.getRuleName());
+      if (ruleClass != null) {
+        if (ruleClass.isDocumented()) {
+          Class<? extends RuleDefinition> ruleDefinition =
+              ruleClassProvider.getRuleClassDefinition(ruleDoc.getRuleName());
+          for (Attribute attribute : ruleClass.getAttributes()) {
+            String attrName = attribute.getName();
+            List<RuleDocumentationAttribute> attributeDocList =
+                attributeDocEntries.get(attrName);
+            if (attributeDocList != null) {
+              // There are attribute docs for this attribute.
+              // Search the closest one in the ancestor graph.
+              // Note that there can be only one 'closest' attribute since we forbid multiple
+              // inheritance of the same attribute in RuleClass.
+              int minLevel = Integer.MAX_VALUE;
+              RuleDocumentationAttribute bestAttributeDoc = null;
+              for (RuleDocumentationAttribute attributeDoc : attributeDocList) {
+                int level = attributeDoc.getDefinitionClassAncestryLevel(ruleDefinition);
+                if (level >= 0 && level < minLevel) {
+                  bestAttributeDoc = attributeDoc;
+                  minLevel = level;
+                }
+              }
+              if (bestAttributeDoc != null) {
+                ruleDoc.addAttribute(bestAttributeDoc);
+              // If there is no matching attribute doc try to add the common.
+              } else if (ruleDoc.getRuleType().equals(RuleType.BINARY)
+                  && PredefinedAttributes.BINARY_ATTRIBUTES.containsKey(attrName)) {
+                ruleDoc.addAttribute(PredefinedAttributes.BINARY_ATTRIBUTES.get(attrName));
+              } else if (ruleDoc.getRuleType().equals(RuleType.TEST)
+                  && PredefinedAttributes.TEST_ATTRIBUTES.containsKey(attrName)) {
+                ruleDoc.addAttribute(PredefinedAttributes.TEST_ATTRIBUTES.get(attrName));
+              } else if (PredefinedAttributes.COMMON_ATTRIBUTES.containsKey(attrName)) {
+                ruleDoc.addAttribute(PredefinedAttributes.COMMON_ATTRIBUTES.get(attrName));
+              }
+            }
+          }
+        }
+      } else {
+        throw ruleDoc.createException("Can't find RuleClass for " + ruleDoc.getRuleName());
+      }
+    }
+  }
+
+  /**
+   * Goes through all the html files and subdirs under inputPath and collects the rule
+   * and attribute documentations using the ruleDocEntries and attributeDocEntries variable.
+   */
+  public void collectDocs(
+      Set<File> processedFiles,
+      Map<String, File> ruleClassFiles,
+      Map<String, RuleDocumentation> ruleDocEntries,
+      ListMultimap<String, RuleDocumentationAttribute> attributeDocEntries,
+      File inputPath) throws BuildEncyclopediaDocException, IOException {
+    if (processedFiles.contains(inputPath)) {
+      return;
+    }
+
+    if (inputPath.isFile()) {
+      if (DocgenConsts.JAVA_SOURCE_FILE_SUFFIX.apply(inputPath.getName())) {
+        SourceFileReader sfr = new SourceFileReader(
+            ruleClassProvider, inputPath.getAbsolutePath());
+        sfr.readDocsFromComments();
+        for (RuleDocumentation d : sfr.getRuleDocEntries()) {
+          String ruleName = d.getRuleName();
+          if (ruleDocEntries.containsKey(ruleName)
+              && !ruleClassFiles.get(ruleName).equals(inputPath)) {
+            System.err.printf("WARNING: '%s' from '%s' overrides value already in map from '%s'\n",
+                d.getRuleName(), inputPath, ruleClassFiles.get(ruleName));
+          }
+          ruleClassFiles.put(ruleName, inputPath);
+          ruleDocEntries.put(ruleName, d);
+        }
+        if (attributeDocEntries != null) {
+          // Collect all attribute documentations from this file.
+          attributeDocEntries.putAll(sfr.getAttributeDocEntries());
+        }
+      }
+    } else if (inputPath.isDirectory()) {
+      for (File childPath : inputPath.listFiles()) {
+        collectDocs(processedFiles, ruleClassFiles, ruleDocEntries, attributeDocEntries, childPath);
+      }
+    }
+
+    processedFiles.add(inputPath);
+  }
+}