1 files changed, 168 insertions, 0 deletions

diff --git a/crates/ra_syntax/src/validation/string.rs b/crates/ra_syntax/src/validation/string.rs
new file mode 100644
index 000000000..089879d15
--- /dev/null
+++ b/crates/ra_syntax/src/validation/string.rs
@@ -0,0 +1,168 @@
+use crate::{
+    ast::{self, AstNode},
+    string_lexing::{self, StringComponentKind},
+    yellow::{
+        SyntaxError,
+        SyntaxErrorKind::*,
+    },
+};
+
+use super::char;
+
+pub(crate) fn validate_string_node(node: ast::String, errors: &mut Vec<SyntaxError>) {
+    let literal_text = node.text();
+    let literal_range = node.syntax().range();
+    let mut components = string_lexing::parse_string_literal(literal_text);
+    for component in &mut components {
+        let range = component.range + literal_range.start();
+
+        match component.kind {
+            StringComponentKind::Char(kind) => {
+                // Chars must escape \t, \n and \r codepoints, but strings don't
+                let text = &literal_text[component.range];
+                match text {
+                    "\t" | "\n" | "\r" => { /* always valid */ }
+                    _ => char::validate_char_component(text, kind, range, errors),
+                }
+            }
+            StringComponentKind::IgnoreNewline => { /* always valid */ }
+        }
+    }
+
+    if !components.has_closing_quote {
+        errors.push(SyntaxError::new(UnclosedString, literal_range));
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use crate::SourceFileNode;
+
+    fn build_file(literal: &str) -> SourceFileNode {
+        let src = format!(r#"const S: &'static str = "{}";"#, literal);
+        println!("Source: {}", src);
+        SourceFileNode::parse(&src)
+    }
+
+    fn assert_valid_str(literal: &str) {
+        let file = build_file(literal);
+        assert!(
+            file.errors().len() == 0,
+            "Errors for literal '{}': {:?}",
+            literal,
+            file.errors()
+        );
+    }
+
+    fn assert_invalid_str(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'\"' | b'\\' => { /* Ignore string close and backslash */ }
+                _ => assert_valid_str(&(byte as char).to_string()),
+            }
+        }
+    }
+
+    #[test]
+    fn test_unicode_codepoints() {
+        let valid = ["Ƒ", "バ", "メ", "﷽"];
+        for c in &valid {
+            assert_valid_str(c);
+        }
+    }
+
+    #[test]
+    fn test_unicode_multiple_codepoints() {
+        let valid = ["नी", "👨‍👨‍"];
+        for c in &valid {
+            assert_valid_str(c);
+        }
+    }
+
+    #[test]
+    fn test_valid_ascii_escape() {
+        let valid = [r"\'", r#"\""#, r"\\", r"\n", r"\r", r"\t", r"\0", "a", "b"];
+        for c in &valid {
+            assert_valid_str(c);
+        }
+    }
+
+    #[test]
+    fn test_invalid_ascii_escape() {
+        let invalid = [r"\a", r"\?", r"\"];
+        for c in &invalid {
+            assert_invalid_str(c);
+        }
+    }
+
+    #[test]
+    fn test_valid_ascii_code_escape() {
+        let valid = [r"\x00", r"\x7F", r"\x55"];
+        for c in &valid {
+            assert_valid_str(c);
+        }
+    }
+
+    #[test]
+    fn test_invalid_ascii_code_escape() {
+        let invalid = [r"\x", r"\x7", r"\xF0"];
+        for c in &invalid {
+            assert_invalid_str(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_str(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_str(c);
+        }
+    }
+
+    #[test]
+    fn test_mixed() {
+        assert_valid_str(
+            r"This is the tale of a string
+with a newline in between, some emoji (👨‍👨‍) here and there,
+unicode escapes like this: \u{1FFBB} and weird stuff like
+this ﷽",
+        );
+    }
+
+    #[test]
+    fn test_ignore_newline() {
+        assert_valid_str(
+            "Hello \
+             World",
+        );
+    }
+}