From 41275c06c58c91aa216300f39e0557153667d965 Mon Sep 17 00:00:00 2001
From: Jason Dreyzehner <jason@dreyzehner.com>
Date: Wed, 21 Aug 2019 11:34:15 -0400
Subject: [PATCH] fix(compiler): allow empty programs to be compiled

---
 .../auth/templates/language/compile.spec.ts   | 159 +++++++++++++++++-
 src/lib/auth/templates/language/compile.ts    |  18 --
 src/lib/auth/templates/language/resolve.ts    |   9 +-
 3 files changed, 157 insertions(+), 29 deletions(-)

diff --git a/src/lib/auth/templates/language/compile.spec.ts b/src/lib/auth/templates/language/compile.spec.ts
index 746a1bb9..73dbb873 100644
--- a/src/lib/auth/templates/language/compile.spec.ts
+++ b/src/lib/auth/templates/language/compile.spec.ts
@@ -3,7 +3,7 @@ import test from 'ava';
 
 import { hexToBin } from '../../../utils/hex';
 
-import { compileScript } from './compile';
+import { compileScript, compileScriptText } from './compile';
 
 test('compileScript: unprovided ID', t => {
   t.deepEqual(compileScript('test', {}, { scripts: { typo: '1' } }), {
@@ -26,19 +26,160 @@ test('compileScript: unprovided ID', t => {
 
 test('compileScript: empty string', t => {
   t.deepEqual(compileScript('t', {}, { scripts: { t: '' } }), {
-    errorType: 'parse',
-    errors: [
+    bytecode: Uint8Array.of(),
+    parse: {
+      end: {
+        column: 1,
+        line: 1,
+        offset: 0
+      },
+      name: 'Script',
+      start: {
+        column: 1,
+        line: 1,
+        offset: 0
+      },
+      value: []
+    },
+    reduce: {
+      bytecode: Uint8Array.of(),
+      range: {
+        endColumn: 1,
+        endLineNumber: 1,
+        startColumn: 1,
+        startLineNumber: 1
+      },
+      source: [
+        {
+          bytecode: Uint8Array.of(),
+          range: {
+            endColumn: 1,
+            endLineNumber: 1,
+            startColumn: 1,
+            startLineNumber: 1
+          }
+        }
+      ]
+    },
+    resolve: [
       {
-        error: 'Tried to compile an empty string as a script.',
         range: {
-          endColumn: 0,
-          endLineNumber: 0,
-          startColumn: 0,
-          startLineNumber: 0
+          endColumn: 1,
+          endLineNumber: 1,
+          startColumn: 1,
+          startLineNumber: 1
+        },
+        type: 'comment',
+        value: ''
+      }
+    ],
+    success: true
+  });
+});
+
+test('compileScriptText: empty string', t => {
+  t.deepEqual(compileScriptText('', {}, { scripts: {} }), {
+    bytecode: Uint8Array.of(),
+    parse: {
+      end: {
+        column: 1,
+        line: 1,
+        offset: 0
+      },
+      name: 'Script',
+      start: {
+        column: 1,
+        line: 1,
+        offset: 0
+      },
+      value: []
+    },
+    reduce: {
+      bytecode: Uint8Array.of(),
+      range: {
+        endColumn: 1,
+        endLineNumber: 1,
+        startColumn: 1,
+        startLineNumber: 1
+      },
+      source: [
+        {
+          bytecode: Uint8Array.of(),
+          range: {
+            endColumn: 1,
+            endLineNumber: 1,
+            startColumn: 1,
+            startLineNumber: 1
+          }
         }
+      ]
+    },
+    resolve: [
+      {
+        range: {
+          endColumn: 1,
+          endLineNumber: 1,
+          startColumn: 1,
+          startLineNumber: 1
+        },
+        type: 'comment',
+        value: ''
       }
     ],
-    success: false
+    success: true
+  });
+});
+
+test('compileScriptText: empty script (script with space)', t => {
+  t.deepEqual(compileScript('t', {}, { scripts: { t: '    ' } }), {
+    bytecode: Uint8Array.of(),
+    parse: {
+      end: {
+        column: 5,
+        line: 1,
+        offset: 4
+      },
+      name: 'Script',
+      start: {
+        column: 5,
+        line: 1,
+        offset: 4
+      },
+      value: []
+    },
+    reduce: {
+      bytecode: Uint8Array.of(),
+      range: {
+        endColumn: 5,
+        endLineNumber: 1,
+        startColumn: 5,
+        startLineNumber: 1
+      },
+      source: [
+        {
+          bytecode: Uint8Array.of(),
+          range: {
+            endColumn: 5,
+            endLineNumber: 1,
+            startColumn: 5,
+            startLineNumber: 1
+          }
+        }
+      ]
+    },
+    resolve: [
+      {
+        range: {
+          endColumn: 5,
+          endLineNumber: 1,
+          startColumn: 5,
+          startLineNumber: 1
+        },
+        type: 'comment',
+        value: ''
+      }
+    ],
+    success: true
   });
 });
 
diff --git a/src/lib/auth/templates/language/compile.ts b/src/lib/auth/templates/language/compile.ts
index c21f3ba0..dd40295e 100644
--- a/src/lib/auth/templates/language/compile.ts
+++ b/src/lib/auth/templates/language/compile.ts
@@ -83,24 +83,6 @@ export const compileScriptText = <
   environment: CompilationEnvironment<CompilerOperationData>,
   scriptId?: string
 ): CompilationResult<ProgramState> => {
-  // tslint:disable-next-line: no-if-statement
-  if (script.length === 0) {
-    return {
-      errorType: 'parse',
-      errors: [
-        {
-          error: 'Tried to compile an empty string as a script.',
-          range: {
-            endColumn: 0,
-            endLineNumber: 0,
-            startColumn: 0,
-            startLineNumber: 0
-          }
-        }
-      ],
-      success: false
-    };
-  }
   const parseResult = parseScript(script);
   // tslint:disable-next-line: no-if-statement
   if (!parseResult.status) {
diff --git a/src/lib/auth/templates/language/resolve.ts b/src/lib/auth/templates/language/resolve.ts
index 28472477..345267b8 100644
--- a/src/lib/auth/templates/language/resolve.ts
+++ b/src/lib/auth/templates/language/resolve.ts
@@ -84,9 +84,9 @@ enum Constants {
 export const resolveScriptSegment = (
   segment: BitAuthScriptSegment,
   resolveIdentifiers: IdentifierResolutionFunction
-): ResolvedScript =>
+): ResolvedScript => {
   // tslint:disable-next-line: cyclomatic-complexity
-  segment.value.map(child => {
+  const resolved = segment.value.map(child => {
     const range = pluckRange(child);
     switch (child.name) {
       case 'Identifier':
@@ -159,6 +159,11 @@ export const resolveScriptSegment = (
     }
   });
 
+  return resolved.length === 0
+    ? [{ range: pluckRange(segment), type: 'comment' as 'comment', value: '' }]
+    : resolved;
+};
+
 /**
  * Returns the bytecode result on success or an error message on failure.
  */