Add support for LGTM_INDEX_FILTERS

src/analysis-paths.test.ts

@@ -11,6 +11,7 @@ test("emptyPaths", async t => {
   analysisPaths.includeAndExcludeAnalysisPaths(config, []);
   t.is(process.env['LGTM_INDEX_INCLUDE'], undefined);
   t.is(process.env['LGTM_INDEX_EXCLUDE'], undefined);
+  t.is(process.env['LGTM_INDEX_FILTERS'], undefined);
 });
 
 test("nonEmptyPaths", async t => {
@@ -20,4 +21,5 @@ test("nonEmptyPaths", async t => {
   analysisPaths.includeAndExcludeAnalysisPaths(config, []);
   t.is(process.env['LGTM_INDEX_INCLUDE'], 'path1\npath2');
   t.is(process.env['LGTM_INDEX_EXCLUDE'], 'path3\npath4');
+  t.is(process.env['LGTM_INDEX_FILTERS'], 'include:path1\ninclude:path2\nexclude:path3\nexclude:path4');
 });

src/analysis-paths.ts

@@ -2,22 +2,40 @@ import * as core from '@actions/core';
 
 import * as configUtils from './config-utils';
 
+function isInterpretedLanguage(language): boolean {
+  return language === 'javascript' || language === 'python';
+}
+
 export function includeAndExcludeAnalysisPaths(config: configUtils.Config, languages: string[]) {
+  // The 'LGTM_INDEX_INCLUDE' and 'LGTM_INDEX_EXCLUDE' environment variables
+  // control which files/directories are traversed when scanning.
+  // This allows including files that otherwise would not be scanned, or
+  // excluding and not traversing entire file subtrees.
+  // It does not understand double-globs because that would require it to
+  // traverse the entire file tree to determine which files are matched.
   if (config.paths.length !== 0) {
     core.exportVariable('LGTM_INDEX_INCLUDE', config.paths.join('\n'));
   }
-
   if (config.pathsIgnore.length !== 0) {
     core.exportVariable('LGTM_INDEX_EXCLUDE', config.pathsIgnore.join('\n'));
   }
 
-  function isInterpretedLanguage(language): boolean {
-    return language === 'javascript' || language === 'python';
+  // The 'LGTM_INDEX_FILTERS' environment variable controls which files are
+  // extracted or ignored. It does not control which directories are traversed.
+  // This does understand the double-glob syntax.
+  const filters: string[] = [];
+  filters.push(...config.paths.map(p => 'include:' + p));
+  filters.push(...config.pathsIgnore.map(p => 'exclude:' + p));
+  if (filters.length !== 0) {
+    core.exportVariable('LGTM_INDEX_FILTERS', filters.join('\n'));
   }
 
-  // Index include/exclude only work in javascript and python
-  // If some other language is detected/configured show a warning
-  if ((config.paths.length !== 0 || config.pathsIgnore.length !== 0) && !languages.every(isInterpretedLanguage)) {
+  // Index include/exclude/filters only work in javascript and python.
+  // If any other languages are detected/configured then show a warning.
+  if ((config.paths.length !== 0 ||
+        config.pathsIgnore.length !== 0 ||
+        filters.length !== 0) &&
+      !languages.every(isInterpretedLanguage)) {
     core.warning('The "paths"/"paths-ignore" fields of the config only have effect for Javascript and Python');
   }
 }