feat(recursive): full recursive support (#37)

* feat(recursive): support for evaluating expressions surrounded by arbitary non-expression strings

* feat(recursive): support for evaluating expressions surrounded by arbitary non-expression strings

* feat(recursive): full recursion support

* feat(recursive): full recursion support

.vscode/launch.json

@@ -26,7 +26,9 @@
       "type": "node",
       "request": "launch",
       "args": [
-        "${relativeFile}"
+        "${relativeFile}",
+        "-sstaging",
+        "-fexample/env.yml"
       ],
       "runtimeArgs": [
         "--nolazy",

README.md

@@ -32,6 +32,7 @@ default_env: &default_env
   OPTIONAL_VARIABLE:  ## Optional variable syntax.  Undefined variables will otherwise cause failures
     value: ${env:SOME_POSSIBLY_UNDEFINED_VARIABLE}
     optional: true
+  ADVANCED_VALUE:  test-${env:SOME_ENV_VARIABLE}
 
 development:
   <<: *default_env
@@ -49,6 +50,16 @@ Then, run `yarn dotenvi -s <stage>` to generate a `.env` file for the stage desi
 Note that stages are not required in your yaml file - you can also define it without stages, in which case you should not specify a stage with the `-s` option when you run `dotenvi`.
 
 
+## Recursion
+
+Dotenvi now supports recursion.  You can specify an expression that returns another expression.  For example, if the following environment variables are defined:
+
+* `RECURSIVE_OUTER`: `${env:RECURSIVE_MIDDLE}-test`
+* `RECURSIVE_MIDDLE`: `foo${env:RECURSIVE_INNER}bar${env:RECURSIVE_INNER}`
+* `RECURSIVE_INNER`: `test`
+
+If you evaluate `${env:RECURSIVE_OUTER}`, it will return `footestbartest-test`.
+
 ## Configuration
 
 In order to override default configuration, you can supply a `env.js` located next to your `env.yml`.  The format of this file is as follows:
@@ -84,5 +95,3 @@ The reference syntax used in `env.yml` is inspired by [serverless](https://githu
 ## Possible Future Work
 
 1. Allow for `dotenvi` to replace `dotenv`, if desired, by skipping the `.env`-generation step.
-2. Support for references embedded within a configuration value (e.g., `foo-${env:BAR}` --> `foo-bar` if BAR=bar)
-3. Support recursive reference calls (e.g., `${env:${env:FOO}}`)

example/env.yml

@@ -10,6 +10,7 @@ default_env: &default_env
   INTEGER_VALUE: 3000
   BOOLEAN_TRUE_VALUE: true
   BOOLEAN_FALSE_VALUE: false
+  VALUE_WITH_SURROUNDING_STRINGS: test-${IA_ENV}-test
 
 sandbox:
   <<: *default_env

src/rewriter.test.js

@@ -33,4 +33,49 @@ describe('Rewriter', () => {
     });
   });
 
+  it('Rewrites variables with surrounding strings', () => {
+    process.env['TEST'] = 'hello';
+    const document = {
+      'test': {
+        'value': 'test-${env:TEST}-test'
+      }
+    };
+
+    const rewriter = new Rewriter({ resolvers: resolvers });
+    return rewriter.rewrite(document).then((output) => {
+      expect(output['test']).toBe('test-hello-test');
+    });
+  });
+
+  it('Handles recursive rewrites', () => {
+    process.env['RECURSIVE_OUTER'] = '${env:RECURSIVE_INNER}';
+    process.env['RECURSIVE_INNER'] = 'test';
+    const document = {
+      'test': {
+        'value': '${env:RECURSIVE_OUTER}'
+      }
+    };
+
+    const rewriter = new Rewriter({ resolvers: resolvers });
+    return rewriter.rewrite(document).then((output) => {
+      expect(output['test']).toBe('test');
+    });
+  });
+
+
+  it('Handles complex recursive rewrites', () => {
+    process.env['RECURSIVE_OUTER2'] = '${env:RECURSIVE_MIDDLE2}-test';
+    process.env['RECURSIVE_MIDDLE2'] = 'foo${env:RECURSIVE_INNER2}bar${env:RECURSIVE_INNER2}'
+    process.env['RECURSIVE_INNER2'] = 'test';
+    const document = {
+      'test': {
+        'value': '${env:RECURSIVE_OUTER2}'
+      }
+    };
+
+    const rewriter = new Rewriter({ resolvers: resolvers });
+    return rewriter.rewrite(document).then((output) => {
+      expect(output['test']).toBe('footestbartest-test');
+    });
+  })
 });

src/rewriter.ts

@@ -15,15 +15,35 @@ export class Rewriter {
 
   private async rewriteValue(value: Primitive): Promise<Primitive> {
     if (typeof value === 'string') {
-      const regex = new RegExp('\\${([a-z]+):(.*)}');
-      const results = value.match(regex);
-      const resolverName = results && results[1];
-      const innerValue = results ? results[2] : value;
-      const resolver = this.getResolver(resolverName);
-      if (!resolver) {
-        throw new Error(`Could not locate resolver for value ${value}`);
+      let result = '';
+      let capture = '';
+
+      for (let i = 0; i < value.length; ++i) {
+        const c = value.charAt(i);
+        if (c === '$') {
+          capture += c;
+        } else if (c == '}') {
+          capture += c;
+          const regex = new RegExp('\\${([a-z]+):(.*)}');
+          const matchResults = capture.match(regex);
+          const resolverName = matchResults && matchResults[1];
+          const resolver = this.getResolver(resolverName);
+          if (!resolver) {
+            throw new Error(`Could not locate resolver for value ${value}`);
+          }
+          const innerValue = matchResults ? matchResults[2] : value;
+          let innerResult = await resolver(innerValue, this.config);
+          if (!innerResult) {
+            throw new Error(`Resolver ${resolverName} didn't return any value`);
+          }
+          result += await this.rewriteValue(innerResult);
+          capture = '';
+        } else if (capture) {
+          capture += c;
+        } else {
+          result += c;
+        }
       }
-      const result = await resolver(innerValue, this.config);
       return result;
     } else {
       return value;