3 files changed, 93 insertions, 8 deletions

diff --git a/crates/ra_syntax/src/string_lexing/mod.rs b/crates/ra_syntax/src/string_lexing/mod.rs
index f0812ff28..cc53e0aba 100644
--- a/crates/ra_syntax/src/string_lexing/mod.rs
+++ b/crates/ra_syntax/src/string_lexing/mod.rs
@@ -219,7 +219,7 @@ mod tests {
 
     #[test]
     fn test_unicode_escapes() {
-        let unicode_escapes = &[r"{DEAD}", "{BEEF}", "{FF}", ""];
+        let unicode_escapes = &[r"{DEAD}", "{BEEF}", "{FF}", "{}", ""];
         for escape in unicode_escapes {
             let escape_sequence = format!(r"'\u{}'", escape);
             let component = closed_char_component(&escape_sequence);
diff --git a/crates/ra_syntax/src/validation.rs b/crates/ra_syntax/src/validation.rs
index 009f5052f..a550ce0ab 100644
--- a/crates/ra_syntax/src/validation.rs
+++ b/crates/ra_syntax/src/validation.rs
@@ -1,3 +1,5 @@
+use std::u32;
+
 use crate::{
     algo::visit::{visitor_ctx, VisitorCtx},
     ast::{self, AstNode},
@@ -42,15 +44,82 @@ 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 = String::new();
+                let mut closed = false;
+                for c in text[3..].chars() {
+                    assert!(!closed, "no characters after escape is closed");
+
+                    if c.is_digit(16) {
+                        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;
+                }
+
+                if code.len() > 6 {
+                    errors.push(SyntaxError::new(OverlongUnicodeEscape, range));
+                }
+
+                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));
+                    }
+                }
+
+                // FIXME: we really need tests for this
             }
             // Code points are always valid
             CodePoint => (),
diff --git a/crates/ra_syntax/src/yellow/syntax_error.rs b/crates/ra_syntax/src/yellow/syntax_error.rs
index f3df6bc15..9aed9e81e 100644
--- a/crates/ra_syntax/src/yellow/syntax_error.rs
+++ b/crates/ra_syntax/src/yellow/syntax_error.rs
@@ -69,6 +69,14 @@ pub enum SyntaxErrorKind {
     LongChar,
     EmptyAsciiEscape,
     InvalidAsciiEscape,
+    TooShortAsciiCodeEscape,
+    AsciiCodeEscapeOutOfRange,
+    MalformedAsciiCodeEscape,
+    UnclosedUnicodeEscape,
+    MalformedUnicodeEscape,
+    EmptyUnicodeEcape,
+    OverlongUnicodeEscape,
+    UnicodeEscapeOutOfRange,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
@@ -83,6 +91,14 @@ impl fmt::Display for SyntaxErrorKind {
             EmptyChar => write!(f, "Empty char literal"),
             UnclosedChar => write!(f, "Unclosed char literal"),
             LongChar => write!(f, "Char literal should be one character long"),
+            TooShortAsciiCodeEscape => write!(f, "Escape sequence should have two digits"),
+            AsciiCodeEscapeOutOfRange => write!(f, "Escape sequence should be between \\x00 and \\x7F"),
+            MalformedAsciiCodeEscape => write!(f, "Escape sequence should be a hexadecimal number"),
+            UnclosedUnicodeEscape => write!(f, "Missing `}}`"),
+            MalformedUnicodeEscape => write!(f, "Malformed unicode escape sequence"),
+            EmptyUnicodeEcape => write!(f, "Empty unicode escape sequence"),
+            OverlongUnicodeEscape => write!(f, "Unicode escape sequence should have at most 6 digits"),
+            UnicodeEscapeOutOfRange => write!(f, "Unicode escape code should be at most 0x10FFFF"),
             ParseError(msg) => write!(f, "{}", msg.0),
         }
     }