Merge branch 'master' of github.com:mug1wara26/source-lsp

Author: mug1wara26

server/src/rules/README.md

@@ -0,0 +1,382 @@
+# Rules
+Documentation for all diagnostics sent back to the client.
+## Warnings
+
+### [No unused variables](ast.ts)
+**Error message**: `Unused name`
+
+Flags variables that are declared but not used within the code.
+```javascript
+const pi = 3.14;
+display(5*5*3.14);
+```
+The variable `pi` should have a warning.
+
+## Errors
+
+### [Missing semicolon](ast.ts)  
+**Error message**: `Missing semicolon`
+
+Identifies statements that are missing semicolons.
+```javascript
+const x = 1;
+```
+The line ending should have an error.
+
+### [Trailing comma](ast.ts)  
+**Error message**: `Trailing comma`
+
+Identifies expressions that have trailing commas.
+```javascript
+const x = [1,2,3,];
+```
+The comma after `3` should have an error.
+
+### [No namespace/default imports](ast.ts)  
+**Error message**: `Only normal imports are allowed`
+
+Bans namespace and default imports.
+```javascript
+import * as rune from "rune";
+import black from "rune";
+```
+Both lines will throw an error around the identifier.
+
+### [Unexpected token in function parameters](ast.ts) 
+**Error message**: `Unexpected token`
+
+Only allows identifiers as function parameters
+```javascript
+function foo(a+b) {}
+```
+`a+b` will throw an error.
+
+### [Redeclaration of variables](ast.ts)  
+**Error message**: `Identifier '${name}' has already been declared`
+
+Bans redeclaration of names in the same scope
+```javascript
+let x = 1;
+let x = 2;
+```
+The second `x` will throw an error.
+
+### [No array expressions](rules/arrayExpression.ts)  
+**Error message**: `Array expressions are not allowed`
+
+Bans array expressions before Source 3
+```javascript
+const x = [1,2,3];
+```
+The array `[1,2,3];` will throw an error.
+
+### [No empty elements](rules/arrayExpression.ts)
+**Error message**: `No holes are allowed in array literals`
+
+Bans empty elements in array expressions
+```javascript
+[1,,3];
+```
+The array `[1,,3]` will throw an error.
+
+### [Constant reassignment](rules/assignmentExpression.ts)
+**Error message**: `Cannot assign new value to constant ${name}`
+
+Bans reassignment to constant variable
+```javascript
+const x = 1;
+x = 2;
+```
+The second `x` will throw an error
+
+### [Incomplete binary expression](rules/binaryExpression.ts)
+**Error message**: `Incomplete binary expression`
+
+Detects when a binary expression is missing a left/right node
+```javascript
+10 + ;
+5 === ;
+```
+Both lines will throw an error
+
+### [Force strict equality](rules/binaryExpression.ts)
+**Error message**: `Use ===/!== instead of ==/!=`
+
+Bans the use of loose equality checks `==` and `!=`
+```javascript
+true == 1;
+```
+
+### [Disallowed operators](rules/binaryExpression.ts)
+**Error message**: `${operator} is not allowed`
+
+Only permitted operators defined in Source is allowed. Binary operators like `^` or `instanceof` is banned, unary operators like `typeof` is also banned.
+```javascript
+100^5;
+typeof 1 === "number"
+```
+The two expressions will throw an error.
+
+### [Only string or number in equality checks](rules/binaryExpression.ts)
+**Error message**: `Expected string or number on left/right hand side of operation, got ${type}`
+
+Before Source 3, only strings or numbers can be in equality checks
+```javascript
+true === 1; // Expected string or number on left hand side of operation, got boolean
+true === (1 === 1); // Expected string or number on left hand side of operation, got boolean
+(1 === 1) === undefined; // Expected string or number on right hand side of operation, got undefined
+"string" === 1; // Expected string on left hand side of operation, got number
+```
+Errors are shown in the comments.
+
+### [No break statements](rules/breakStatement.ts)
+**Error message**: `Break statements are not allowed;`
+
+No break statements before Source 3
+```javascript
+break;
+```
+`break` will throw an error.
+
+### [Calling a non function](rules/callExpression.ts)  
+**Error message**: `${name} is not a function`
+
+Cannot call identifiers that are not a function
+```javascript
+const x = 1;
+x();
+let y = 1;
+y()
+```
+The function application on `x` will throw an error, however the function application on `y` will not, as y 
+can be reassigned, hence it will be a runtime error.
+
+### [Not enough parameters](rules/callExpression.ts)  
+**Error message**: `Expected ${num_args} or more arguments, but got ${num_supplied_args}`
+
+Detects when a function application has not enough parameters. Currently does not work for anonymous lambdas.
+```javascript
+display();
+```
+The call to `display` needs at least 1 element.
+
+### [Incomplete ternary](rules/conditionalExpression.ts)  
+**Error message**: `Incomplete ternary`
+
+Detects when a ternary does not have a consequent or alternate case.
+```javascript
+b => b ? 1;
+```
+`b ? 1` throws an error, as there is no alternate case.
+
+### [No continue statements](rules/continueStatement.ts)
+**Error message**: `Continue statements are not allowed`
+
+Bans continue statements before Source 3
+```javascript
+continue;
+```
+`continue` will throw an error.
+
+### [No for statements](rules/forStatement.ts)
+**Error message**: `For statements are not allowed`
+
+Bans for statements before Source 3
+```javascript
+for(let i = 0; i < 10; i++) {}
+```
+`for(...)` will throw an error.
+
+### [Missing block statements](rules/forStatement.ts)
+**Error message**: `Missing curly braces around for/while/if/else`
+
+Detects missing curly braces for some statements
+```javascript
+if (1 === 1)
+  display("1 is equal to 1");
+```
+The whole expression will throw an error.
+
+### [Incomplete for loop](rules/forStatement.ts)
+**Error message**: `Incomplete for loop`
+
+Detects if a for loop is missing any parts
+```javascript
+for (let i = 0; i < 10;) {
+}
+```
+`for(...)` will throw an error.
+
+### [Missing function name](rules/functionDeclaration.ts)  
+**Error message**: `Missing function name`
+
+Detects if function declaration is incomplete
+```javascript
+function () {}
+```
+The whole expression will throw an error.
+
+### [Terminal rest element](rules/functionDeclaration.ts)  
+**Error message**: `No params allowed after rest element`
+
+If a function has a rest parameter, it must be the last parameter.
+```javascript
+function foo(arg1, ...arg2, arg3) {}
+(arg1, ...arg2, arg3) => {};
+```
+Both cases will throw an error around `arg3`
+
+### [Identifier not declared](rules/identifier.ts)
+**Error message**: `Name ${name} not declared`
+
+Detects if there is a declaration for an identifier in its scope.
+```javascript
+{
+  const x = 1;
+  {
+    display(x);
+  }
+}
+display(x);
+```
+The first `x` in `display(x)` should not throw an error, but the second one should.
+
+### [Missing else case](rules/ifStatement.ts)  
+**Error message**: `Missing "else" in "if-else" statement`
+
+`else` case is required in an if statement before Source 3
+```javascript
+if (true) {
+  display("hello world");
+}
+```
+An error will be thrown around the body of the if statement.
+
+### [No module name](rules/importDeclaration.ts)
+**Error message**: `Expected module name`
+
+Imports require the module name.
+```javascript
+import { black }
+```
+An error will be thrown around the whole import statement.
+
+### [Missing closing string](rules/literal.ts)  
+**Error message**: `Incomplete string expression`
+
+Strings must be closed within the same line
+```javascript
+"hello world
+";
+```
+An error will be thrown on both lines.
+
+### [No null literals](rules/literal.ts)  
+**Error message**: `Null literals are not allowed`
+
+Nulls are not allowed in Source 1.
+```javascript
+display(null);
+```
+An error will be thrown around `null`.
+
+### [No member access](rules/memberExpression.ts)  
+**Error message**: `Member access expressions are not allowed`
+
+Member access with square brackets `[]` is not allowed before source 3.
+```javascript
+"hello world"[0];
+```
+An error will be thrown around the whole expression.
+
+### [No dot abbreviations](rules/memberExpression.ts)  
+**Error message**: `No dot abbreviations`
+
+Source prohibits usage of dot access in any case.
+```javascript
+display("hello world".length);
+```
+An error will be thrown around the whole expression.
+
+### [Non integer member access](rules/memberExpression.ts)  
+**Error message**: `Expected integer as array index, got ${type}`
+
+Array access must use non negative integers
+```javascript
+const arr = [1,2,3];
+arr[undefined]; // Expected non negative integer as array index, got undefined.
+arr["test"]; // Expected non negative integer as array index, got string.
+arr[1.1]; // Expected non negative integer as array index, got float.
+arr[-1]; // Expected non negative integer as array index, got negative number.
+```
+Errors are shown in the comments.
+
+### [No return value](rules/returnStatement.ts)  
+**Error message**: `Missing value in return statement`
+
+Returns statements must return a value in Source.
+```javascript
+function foo() {
+  return;
+}
+```
+An error will be thrown around the `return` statement.
+
+### [No spread syntax](rules/spreadElement.ts)  
+**Error message**: `Spread syntax is only allowed when supplying arguments to a function`
+
+The spread syntax `...` can only be used directly inside a function call as a parameter.
+```javascript
+const x = [1,2,3];
+display(list(...x)); // Valid
+display(list((...x)); // Not valid
+```
+The second use of the spread syntax will throw an error.
+
+### [No expressions in template literals](rules/templateLiteral.ts)
+**Error message**: `Expressions not allowed in template literal`
+
+In Source, template literals are only used for multiline string, they cannot contain expressions.
+```javascript
+const x = `10 * 10 = ${10*10}`
+```
+The expression `10*10` will throw an error.
+
+### [No multiple declarations](rules/variableDeclaration.ts)  
+**Error message**: `Multiple declarations not allowed`
+
+In Source, only 1 declaration is allowed in each variable declarator.
+```javascript
+const x = 1, y = 2, z = 3;
+```
+The whole statement will throw an error.
+
+### [Incomplete variable declaration](rules/variableDeclaration.ts)
+**Error message**: `Incomplete variable declaration`
+
+Detects whether left and right side of variable declaration in present;
+```javascript
+const x;
+```
+The whole statement will throw an error.
+
+### [No let declaration](rules/variableDeclaration.ts)  
+**Error message**: `Use keyword "const" instead to declare a constant`
+
+Before Source 3, variables can only be declared with `const`
+```javascript
+let x = 1;
+```
+The whole statement will throw an error.
+
+### [No while statement](rules/whileStatement.ts)  
+**Error message**: `While statements are not allowed`
+
+Before Source 3, while statements are not allowed.
+```javascript
+while(true) {
+  display("hi")
+}
+```
+`while(...)` will throw an error.
+