Merge pull request #487 from HigherOrderCO/478-dont-allow-variable-na…

…mes-to-contain-__

478 dont allow variable names to contain "__"

Cargo.toml

@@ -2,7 +2,7 @@
 name = "bend-lang"
 description = "A high-level, massively parallel programming language"
 license = "Apache-2.0"
-version = "0.2.18"
+version = "0.2.19"
 edition = "2021"
 exclude = ["tests/snapshots/"]
 

docs/syntax.md

@@ -46,7 +46,7 @@ def main:
 
 A function definition is composed by a name, a sequence of parameters and a body.
 
-A top-level name can be anything matching the regex `[A-Za-z0-9_.-/]+`, except it can't have `__` (used for generated names).
+A top-level name can be anything matching the regex `[A-Za-z0-9_.-/]+`, except it can't have `__` (used for generated names) or start with `//`.
 
 The last statement of each function must either be a `return` or a selection statement (`if`, `switch`, `match`, `fold`)
 where all branches `return`.
@@ -372,7 +372,10 @@ some_var
 foo/bar
 ```
 
-A variable can be anything matching the regex `[A-Za-z0-9_.-/]+`.
+A variable can be anything matching the regex `[A-Za-z0-9_.-/]+` but with some restrictions:
+
+- It can not start with `//`
+- It can not contain `__`
 
 A variable is a name for some immutable expression. It is possible to rebind variables with the same name.
 
@@ -618,7 +621,7 @@ Name (Ctr1 sub_arg1 sub_arg2) arg3 = rule0_body
 Name Ctr2 arg3 = rule1_body
 ```
 
-A top-level name can be anything matching the regex `[A-Za-z0-9_.-/]+`, except it can't have `__` (used for generated names).
+A top-level name can be anything matching the regex `[A-Za-z0-9_.-/]+`, except it can't have `__` (used for generated names) or start with `//`.
 
 ### Function Definitions
 
@@ -681,7 +684,10 @@ The constructors inherit the name of their types and become functions (`Tree/Nod
 
 ### Variables
 
-A variable can be anything matching the regex `[A-Za-z0-9_.-/]+`.
+A variable can be anything matching the regex `[A-Za-z0-9_.-/]+` but with some restrictions:
+
+- It can not start with `//`
+- It can not contain `__`
 
 A variable is a name for some immutable expression. It is possible to rebind variables with the same name.
 

src/fun/parser.rs

@@ -805,24 +805,31 @@ pub trait ParserCommons<'a>: Parser<'a> {
     }
   }
 
-  fn parse_top_level_name(&mut self) -> ParseResult<Name> {
+  fn parse_restricted_name(&mut self, kind: &str) -> ParseResult<Name> {
     let ini_idx = *self.index();
-    let nam = self.parse_bend_name()?;
+    let name = self.take_while(|c| c.is_ascii_alphanumeric() || c == '_' || c == '.' || c == '-' || c == '/');
+    if name.is_empty() {
+      self.expected("name")?
+    }
+    let name = Name::new(name.to_owned());
     let end_idx = *self.index();
-    if nam.contains("__") {
-      let msg = "Top-level names are not allowed to contain \"__\".".to_string();
+    if name.contains("__") {
+      let msg = format!("{kind} names are not allowed to contain \"__\".");
       self.with_ctx(Err(msg), ini_idx, end_idx)
-    } else if nam.starts_with("//") {
-      let msg = "Top-level names are not allowed to start with \"//\".".to_string();
+    } else if name.starts_with("//") {
+      let msg = format!("{kind} names are not allowed to start with \"//\".");
       self.with_ctx(Err(msg), ini_idx, end_idx)
     } else {
-      Ok(nam)
+      Ok(name)
     }
   }
 
+  fn parse_top_level_name(&mut self) -> ParseResult<Name> {
+    self.parse_restricted_name("Top-level")
+  }
+
   fn parse_bend_name(&mut self) -> ParseResult<Name> {
-    let name = self.take_while(|c| c.is_ascii_alphanumeric() || c == '_' || c == '.' || c == '-' || c == '/');
-    if name.is_empty() { self.expected("name") } else { Ok(Name::new(name.to_owned())) }
+    self.parse_restricted_name("Variable")
   }
 
   /// Consumes exactly the text without skipping.

tests/golden_tests/compile_file/variable_name_double_underscore.bend

@@ -0,0 +1,2 @@
+def main:
+  return __this_should_fail__(*)

tests/snapshots/compile_file__variable_name_double_underscore.bend.snap

@@ -0,0 +1,9 @@
+---
+source: tests/golden_tests.rs
+input_file: tests/golden_tests/compile_file/variable_name_double_underscore.bend
+---
+Errors:
+In tests/golden_tests/compile_file/variable_name_double_underscore.bend :
+- expected: expression
+- detected:
+  2 |   return __this_should_fail__(*)