Merge #207

207: Finish implementing char validation r=aochagavia a=aochagavia

The only thing missing right now are good integration tests (and maybe more descriptive error messages)

Co-authored-by: Adolfo Ochagavía <github@adolfo.ochagavia.xyz>

crates/ra_syntax/src/validation.rs

@@ -1,3 +1,7 @@
+use std::u32;
+
+use arrayvec::ArrayString;
+
 use crate::{
     algo::visit::{visitor_ctx, VisitorCtx},
     ast::{self, AstNode},
@@ -42,18 +46,90 @@ fn validate_char(node: ast::Char, errors: &mut Vec<SyntaxError>) {
                 }
             }
             AsciiCodeEscape => {
-                // TODO:
-                // * First digit is octal
-                // * Second digit is hex
+                // An AsciiCodeEscape has 4 chars, example: `\xDD`
+                if text.len() < 4 {
+                    errors.push(SyntaxError::new(TooShortAsciiCodeEscape, range));
+                } else {
+                    assert!(
+                        text.chars().count() == 4,
+                        "AsciiCodeEscape cannot be longer than 4 chars"
+                    );
+
+                    match u8::from_str_radix(&text[2..], 16) {
+                        Ok(code) if code < 128 => { /* Escape code is valid */ }
+                        Ok(_) => errors.push(SyntaxError::new(AsciiCodeEscapeOutOfRange, range)),
+                        Err(_) => errors.push(SyntaxError::new(MalformedAsciiCodeEscape, range)),
+                    }
+                }
             }
             UnicodeEscape => {
-                // TODO:
-                // * Only hex digits or underscores allowed
-                // * Max 6 chars
-                // * Within allowed range (must be at most 10FFFF)
+                assert!(&text[..2] == "\\u", "UnicodeEscape always starts with \\u");
+
+                if text.len() == 2 {
+                    // No starting `{`
+                    errors.push(SyntaxError::new(MalformedUnicodeEscape, range));
+                    return;
+                }
+
+                if text.len() == 3 {
+                    // Only starting `{`
+                    errors.push(SyntaxError::new(UnclosedUnicodeEscape, range));
+                    return;
+                }
+
+                let mut code = ArrayString::<[_; 6]>::new();
+                let mut closed = false;
+                for c in text[3..].chars() {
+                    assert!(!closed, "no characters after escape is closed");
+
+                    if c.is_digit(16) {
+                        if code.len() == 6 {
+                            errors.push(SyntaxError::new(OverlongUnicodeEscape, range));
+                            return;
+                        }
+
+                        code.push(c);
+                    } else if c == '_' {
+                        // Reject leading _
+                        if code.len() == 0 {
+                            errors.push(SyntaxError::new(MalformedUnicodeEscape, range));
+                            return;
+                        }
+                    } else if c == '}' {
+                        closed = true;
+                    } else {
+                        errors.push(SyntaxError::new(MalformedUnicodeEscape, range));
+                        return;
+                    }
+                }
+
+                if !closed {
+                    errors.push(SyntaxError::new(UnclosedUnicodeEscape, range))
+                }
+
+                if code.len() == 0 {
+                    errors.push(SyntaxError::new(EmptyUnicodeEcape, range));
+                    return;
+                }
+
+                match u32::from_str_radix(&code, 16) {
+                    Ok(code_u32) if code_u32 > 0x10FFFF => {
+                        errors.push(SyntaxError::new(UnicodeEscapeOutOfRange, range));
+                    }
+                    Ok(_) => {
+                        // Valid escape code
+                    }
+                    Err(_) => {
+                        errors.push(SyntaxError::new(MalformedUnicodeEscape, range));
+                    }
+                }
+            }
+            CodePoint => {
+                // These code points must always be escaped
+                if text == "\t" || text == "\r" {
+                    errors.push(SyntaxError::new(UnescapedCodepoint, range));
+                }
             }
-            // Code points are always valid
-            CodePoint => (),
         }
     }
 
@@ -72,7 +148,124 @@ fn validate_char(node: ast::Char, errors: &mut Vec<SyntaxError>) {
 
 fn is_ascii_escape(code: char) -> bool {
     match code {
-        '\'' | '"' | 'n' | 'r' | 't' | '0' => true,
+        '\\' | '\'' | '"' | 'n' | 'r' | 't' | '0' => true,
         _ => false,
     }
 }
+
+#[cfg(test)]
+mod test {
+    use crate::File;
+
+    fn build_file(literal: &str) -> File {
+        let src = format!("const C: char = '{}';", literal);
+        File::parse(&src)
+    }
+
+    fn assert_valid_char(literal: &str) {
+        let file = build_file(literal);
+        assert!(
+            file.errors().len() == 0,
+            "Errors for literal '{}': {:?}",
+            literal,
+            file.errors()
+        );
+    }
+
+    fn assert_invalid_char(literal: &str) {
+        let file = build_file(literal);
+        assert!(file.errors().len() > 0);
+    }
+
+    #[test]
+    fn test_ansi_codepoints() {
+        for byte in 0..=255u8 {
+            match byte {
+                b'\n' | b'\r' | b'\t' => assert_invalid_char(&(byte as char).to_string()),
+                b'\'' | b'\\' => { /* Ignore character close and backslash */ }
+                _ => assert_valid_char(&(byte as char).to_string()),
+            }
+        }
+    }
+
+    #[test]
+    fn test_unicode_codepoints() {
+        let valid = ["Ƒ", "バ", "メ", "﷽"];
+        for c in &valid {
+            assert_valid_char(c);
+        }
+    }
+
+    #[test]
+    fn test_unicode_multiple_codepoints() {
+        let invalid = ["नी", "👨‍👨‍"];
+        for c in &invalid {
+            assert_invalid_char(c);
+        }
+    }
+
+    #[test]
+    fn test_valid_ascii_escape() {
+        let valid = [
+            r"\'", "\"", "\\\\", "\\\"", r"\n", r"\r", r"\t", r"\0", "a", "b",
+        ];
+        for c in &valid {
+            assert_valid_char(c);
+        }
+    }
+
+    #[test]
+    fn test_invalid_ascii_escape() {
+        let invalid = [r"\a", r"\?", r"\"];
+        for c in &invalid {
+            assert_invalid_char(c);
+        }
+    }
+
+    #[test]
+    fn test_valid_ascii_code_escape() {
+        let valid = [r"\x00", r"\x7F", r"\x55"];
+        for c in &valid {
+            assert_valid_char(c);
+        }
+    }
+
+    #[test]
+    fn test_invalid_ascii_code_escape() {
+        let invalid = [r"\x", r"\x7", r"\xF0"];
+        for c in &invalid {
+            assert_invalid_char(c);
+        }
+    }
+
+    #[test]
+    fn test_valid_unicode_escape() {
+        let valid = [
+            r"\u{FF}",
+            r"\u{0}",
+            r"\u{F}",
+            r"\u{10FFFF}",
+            r"\u{1_0__FF___FF_____}",
+        ];
+        for c in &valid {
+            assert_valid_char(c);
+        }
+    }
+
+    #[test]
+    fn test_invalid_unicode_escape() {
+        let invalid = [
+            r"\u",
+            r"\u{}",
+            r"\u{",
+            r"\u{FF",
+            r"\u{FFFFFF}",
+            r"\u{_F}",
+            r"\u{00FFFFF}",
+            r"\u{110000}",
+        ];
+        for c in &invalid {
+            assert_invalid_char(c);
+        }
+    }
+}