Add DString building.

sketching/may_2025/name_one.dm

@@ -11,3 +11,7 @@ fn main(x: String) {
         let test = 'oops.';
     };
 }
+
+pub mod test {
+
+}

src/ast/build.rs

@@ -1276,7 +1276,31 @@ fn build_single_quote_string(file_id: usize, pair: Pair<Rule>) -> Literal {
 }
 
 fn build_double_quote_string(file_id: usize, pair: Pair<Rule>) -> Literal {
-    todo!()
+    let mut parts: Vec<DStringPart> = vec![];
+    let inner = pair.into_inner();
+    for inner_pair in inner {
+        match inner_pair.as_rule() {
+            Rule::DStringInner => {
+                parts.push(DStringPart::from_string(inner_pair.as_span().as_str()));
+            }
+            Rule::DStringExpression => {
+                let expression_pair = inner_pair.into_inner().next().unwrap();
+                parts.push(DStringPart::from_expression(expect_and_use(
+                    file_id,
+                    expression_pair,
+                    Rule::Expression,
+                    build_expression,
+                )));
+            }
+            _ => unreachable!(),
+        }
+    }
+
+    if parts.len() == 1 && parts[0].is_string() {
+        Literal::String(parts.pop().unwrap().unwrap_string())
+    } else {
+        Literal::DString(DString(parts))
+    }
 }
 
 fn build_backtick_string(file_id: usize, pair: Pair<Rule>) -> Literal {
@@ -1290,12 +1314,13 @@ mod tests {
     use crate::parser::DeimosParser;
     use indoc::indoc;
 
-    fn assert_builds(src: &str) -> CompilationUnit {
+    fn assert_builds(src: &str) {
         let parse_result = DeimosParser::parse(Rule::CompilationUnit, src);
         if let Err(e) = parse_result {
             panic!("Parsing failed.\n{}", e)
         } else {
-            build_ast(0, parse_result.unwrap().next().unwrap())
+            let ast = build_ast(0, parse_result.unwrap().next().unwrap());
+            dbg!(ast);
         }
     }
 
@@ -1331,4 +1356,24 @@ mod tests {
     fn double_literal() {
         assert_builds("fn main() { 1.0 }");
     }
+
+    #[test]
+    fn d_string_no_expressions() {
+        assert_builds("fn main() { \"Hello, World!\" }");
+    }
+
+    #[test]
+    fn d_string_one_expression() {
+        assert_builds("fn main() { \"${foo}\" }");
+    }
+
+    #[test]
+    fn d_string_literal_and_expression() {
+        assert_builds("fn main() { \"Hello, ${foo}!\" }");
+    }
+    
+    #[test]
+    fn d_string_literal_expression_literal() {
+        assert_builds("fn main() { \"Hello, ${foo}! It is a nice day.\" }");
+    }
 }

src/ast/mod.rs

@@ -599,5 +599,46 @@ pub enum Literal {
     Double(f64),
     USize(usize),
     String(String),
+    DString(DString),
     Boolean(bool),
 }
+
+#[derive(Debug)]
+pub struct DString(pub Vec<DStringPart>);
+
+#[derive(Debug)]
+pub enum DStringPart {
+    String(String),
+    Expression(Box<Expression>),
+}
+
+impl DStringPart {
+    pub fn from_string(s: &str) -> DStringPart {
+        DStringPart::String(String::from(s))
+    }
+    
+    pub fn from_expression(e: Expression) -> DStringPart {
+        DStringPart::Expression(Box::new(e))
+    }
+    
+    pub fn is_string(&self) -> bool {
+        match self {
+            DStringPart::String(_) => true,
+            _ => false,
+        }
+    }
+    
+    pub fn unwrap_string(self) -> String {
+        match self {
+            DStringPart::String(s) => s,
+            _ => panic!(),
+        }
+    }
+    
+    pub fn is_expression(&self) -> bool {
+        match self {
+            DStringPart::Expression(_) => true,
+            _ => false,
+        }
+    }
+}

src/ast/pretty_print.rs

@@ -877,7 +877,30 @@ impl PrettyPrint for Literal {
             Double(d) => writer.writeln_indented(&format!("Double({})", d)),
             USize(u) => writer.writeln_indented(&format!("USize({})", u)),
             String(s) => writer.writeln_indented(&format!("String({})", s)),
+            DString(d_string) => d_string.pretty_print(writer),
             Boolean(b) => writer.writeln_indented(&format!("Boolean({})", b)),
         }
     }
 }
+
+impl PrettyPrint for DString {
+    fn pretty_print(&self, writer: &mut IndentWriter) -> std::io::Result<()> {
+        writer.writeln_indented("DString")?;
+        writer.increase_indent();
+        for part in &self.0 {
+            part.pretty_print(writer)?;
+        }
+        Ok(())
+    }
+}
+
+impl PrettyPrint for DStringPart {
+    fn pretty_print(&self, writer: &mut IndentWriter) -> std::io::Result<()> {
+        writer.writeln_indented("DStringPart")?;
+        writer.increase_indent();
+        match self {
+            DStringPart::String(s) => writer.writeln_indented(&format!("String({})", s)),
+            DStringPart::Expression(e) => e.pretty_print(writer),
+        }
+    }
+}

src/ast/unparse.rs

@@ -1042,7 +1042,32 @@ impl Unparse for Literal {
             Double(d) => writer.write(&format!("{}", d)),
             USize(u) => writer.write(&format!("{}", u)),
             String(s) => writer.write(&format!("\"{}\"", s)),
+            DString(d_string) => d_string.unparse(writer),
             Boolean(b) => writer.write(&format!("{}", b)),
         }
     }
 }
+
+impl Unparse for DString {
+    fn unparse(&self, writer: &mut IndentWriter) -> std::io::Result<()> {
+        writer.write("\"")?;
+        for part in &self.0 {
+            part.unparse(writer)?;
+        }
+        writer.write("\"")?;
+        Ok(())
+    }
+}
+
+impl Unparse for DStringPart {
+    fn unparse(&self, writer: &mut IndentWriter) -> std::io::Result<()> {
+        match self {
+            DStringPart::String(s) => writer.write(s),
+            DStringPart::Expression(e) => {
+                writer.write("${")?;
+                e.unparse(writer)?;
+                writer.write("}")
+            }
+        }
+    }
+}

src/parser/deimos.pest

@@ -795,14 +795,15 @@ StringChar = {
 DStringInner = @{ DStringChar+ }
 
 DStringChar = {
-      !( "\"" | "\\" ) ~ ANY
+      !( "\"" | "\\" | "${" ) ~ ANY
     | "\\" ~ ( "\"" | "\\" | "/" | "b" | "f" | "n" | "r" | "t" | "$" )
     | "\\" ~ ( "u" ~ ASCII_HEX_DIGIT{4} )
 }
 
 DStringExpression = {
-      "$"
+      "${"
-    ~ BlockStatement
+    ~ Expression
+    ~ "}"
 }
 
 BacktickString = {
@@ -815,7 +816,7 @@ BacktickString = {
 BacktickInner = @{ BacktickStringChar+ }
 
 BacktickStringChar = {
-      !( "\\`" | "\\" ) ~ ANY
+      !( "\\`" | "\\" | "${" ) ~ ANY
     | "\\" ~ ( "`" | "\\" | "/" | "b" | "f" | "n" | "r" | "t" | "$" )
     | "\\" ~ ( "u" ~ ASCII_HEX_DIGIT{4} )
 }