feat: allow custom var name for with statement and nesting of files.

docs/docs/files.md

@@ -41,6 +41,14 @@ with("test.txt", "r") {
 // file is out of scope, and will the file will be closed for you
 ```
 
+### Custom name
+It is possible to append `as <name>` before the opening `{` in order to customise the name of the constant within the block.
+```cs
+with("test.txt", "r") as myfile {
+    // file constant is passed in here as myfile, NOT file.
+}
+```
+
 ### Writing to files
 
 There are two methods available when writing to a file: `write()` and `writeLine()`. `write()` simply writes strings to a file, `writeLine()` is exactly the same, except it appends a newline to the passed in string. Both functions return the amount of characters wrote to the file.

ops/checkTests.du

@@ -14,6 +14,7 @@ const ignored = {
     ],
     'files': [
         'read.txt',
+        'read2.txt',
     ],
     'strings': [
         'test',

src/vm/compiler.c

@@ -162,10 +162,10 @@ static void initCompiler(Parser *parser, Compiler *compiler, Compiler *parent, F
     compiler->function = NULL;
     compiler->class = NULL;
     compiler->loop = NULL;
-    compiler->withBlock = false;
     compiler->classAnnotations = NULL;
     compiler->methodAnnotations = NULL;
     compiler->fieldAnnotations = NULL;
+    memset(compiler->locals, 0, sizeof(Local) * UINT8_COUNT);
 
     if (parent != NULL) {
         compiler->class = parent->class;
@@ -312,6 +312,22 @@ static int resolveLocal(Compiler *compiler, LangToken *name, bool inFunction) {
 
     return -1;
 }
+static int resolveFileHandles(Compiler *compiler, bool inFunction, int* out) {
+    // Look it up in the local scopes. Look in reverse order so that the
+    // most nested variable is found first and shadows outer ones.
+    int count = 0;
+    for (int i = compiler->localCount - 1; i >= 0; i--) {
+        Local *local = &compiler->locals[i];
+        if (local->isFile) {
+            if (!inFunction && local->depth == -1) {
+                error(compiler->parser, "Cannot read local variable in its own initializer.");
+            }
+            out[count++] = i;
+        }
+    }
+
+    return count;
+}
 
 // Adds an upvalue to [compiler]'s function with the given properties.
 // Does not add one if an upvalue for that variable is already in the
@@ -2519,38 +2535,41 @@ static void switchStatement(Compiler *compiler) {
 }
 
 static void withStatement(Compiler *compiler) {
-    compiler->withBlock = true;
     consume(compiler, TOKEN_LEFT_PAREN, "Expect '(' after 'with'.");
     expression(compiler);
     consume(compiler, TOKEN_COMMA, "Expect comma");
     expression(compiler);
     consume(compiler, TOKEN_RIGHT_PAREN, "Expect ')' after 'with'.");
-    consume(compiler, TOKEN_LEFT_BRACE, "Expect '{' before with body.");
-
-    beginScope(compiler);
 
     int fileIndex = compiler->localCount;
     Local *local = &compiler->locals[compiler->localCount++];
+
+    if(match(compiler, TOKEN_AS)) {
+        consume(compiler, TOKEN_IDENTIFIER, "Expect identifier.");
+        local->name = compiler->parser->previous;
+    } else {
+        local->name = syntheticToken("file");
+    }
+    consume(compiler, TOKEN_LEFT_BRACE, "Expect '{' before with body.");
+
+    beginScope(compiler);
     local->depth = compiler->scopeDepth;
     local->isUpvalue = false;
-    local->name = syntheticToken("file");
+    local->isFile = true;
     local->constant = true;
 
     emitByte(compiler, OP_OPEN_FILE);
     block(compiler);
     emitBytes(compiler, OP_CLOSE_FILE, fileIndex);
     endScope(compiler);
-    compiler->withBlock = false;
 }
 
-static void checkForFileHandle(Compiler *compiler) {
-    if (compiler->withBlock) {
-        LangToken token = syntheticToken("file");
-        int local = resolveLocal(compiler, &token, true);
+static void closeFileHandles(Compiler *compiler) {
+    int ids[UINT8_COUNT];
+    int count = resolveFileHandles(compiler, true, ids);
 
-        if (local != -1) {
-            emitBytes(compiler, OP_CLOSE_FILE, local);
-        }
+    for (int i = 0; i < count; i++) {
+        emitBytes(compiler, OP_CLOSE_FILE, ids[i]);
     }
 }
 
@@ -2560,7 +2579,7 @@ static void returnStatement(Compiler *compiler) {
     }
 
     if (match(compiler, TOKEN_SEMICOLON)) {
-        checkForFileHandle(compiler);
+        closeFileHandles(compiler);
         emitReturn(compiler);
     } else {
         if (compiler->type == TYPE_INITIALIZER) {
@@ -2570,7 +2589,7 @@ static void returnStatement(Compiler *compiler) {
         expression(compiler);
         consume(compiler, TOKEN_SEMICOLON, "Expect ';' after return value.");
 
-        checkForFileHandle(compiler);
+        closeFileHandles(compiler);
         emitByte(compiler, OP_RETURN);
     }
 }

src/vm/compiler.h

@@ -40,6 +40,8 @@ typedef struct {
 
     // True if it's a constant value.
     bool constant;
+
+    bool isFile;
 } Local;
 
 typedef struct {
@@ -100,7 +102,6 @@ typedef struct Compiler {
     Upvalue upvalues[UINT8_COUNT];
 
     int scopeDepth;
-    bool withBlock;
     ObjDict *classAnnotations;
     ObjDict *methodAnnotations;
     ObjDict *fieldAnnotations;

tests/files/read.du

@@ -18,6 +18,7 @@ class TestFileReading < UnitTest {
         "Dictu is great!\n" +
         "Dictu is great!\n" +
         "Dictu is great!";
+    const EXPECTED2 = "This is another file";
 
     testFileRead() {
         var contents;
@@ -29,6 +30,45 @@ class TestFileReading < UnitTest {
         this.assertType(contents, "string");
         this.assertEquals(contents, TestFileReading.EXPECTED);
     }
+    testFileReadCustomName() {
+        var contents;
+
+        with("tests/files/read.txt", "r") as f {
+            contents = f.read();
+        }
+
+        this.assertType(contents, "string");
+        this.assertEquals(contents, TestFileReading.EXPECTED);
+    }
+    testFileReadNested() {
+        var contents;
+
+        with("tests/files/read.txt", "r") {
+            contents = file.read();
+            with("tests/files/read2.txt", "r") as otherFile {
+                contents += otherFile.read();
+            }
+        }
+
+        this.assertType(contents, "string");
+        this.assertEquals(contents, TestFileReading.EXPECTED + TestFileReading.EXPECTED2);
+    }
+    testFileReadNestedShadow() {
+        var contents;
+
+        with("tests/files/read.txt", "r") {
+            with("tests/files/read2.txt", "r") {
+                contents = file.read();
+            }
+            this.assertType(contents, "string");
+            this.assertEquals(contents, TestFileReading.EXPECTED2);
+            contents += file.read();
+        }
+
+        this.assertType(contents, "string");
+        this.assertEquals(contents, TestFileReading.EXPECTED2 + TestFileReading.EXPECTED);
+    }
+
 }
 
 TestFileReading().run();

tests/files/read2.txt

@@ -0,0 +1 @@
+This is another file

tests/files/write.du

@@ -38,6 +38,22 @@ class TestFileWrite < UnitTest {
             this.assertEquals(file.read(), "Dictu is great!Dictu is great!Dictu is great!");
         }
     }
+    testFileWriteCustomName() {
+        with("tests/files/read.txt", "w") as f {
+            // Save contents to reset the file
+            var count = f.write("Dictu is great!");
+            this.assertEquals(count, 15);
+            count = f.write("Dictu is great!");
+            this.assertEquals(count, 15);
+            count = f.write("Dictu is great!");
+            this.assertEquals(count, 15);
+        }
+
+        with("tests/files/read.txt", "r") as rf {
+            // Save contents to reset the file
+            this.assertEquals(rf.read(), "Dictu is great!Dictu is great!Dictu is great!");
+        }
+    }
 }
 
 TestFileWrite().run();