parser: support constant string expressions and concats

trunk_parser/src/ast.rs

@@ -231,6 +231,7 @@ pub enum Expression {
     Closure(Vec<Param>, Option<Type>, Block),
     ArrowFunction(Vec<Param>, Option<Type>, Box<Self>),
     New(Box<Self>, Vec<Self>),
+    ConstantString(String),
 }
 
 #[derive(Debug, Clone, PartialEq, Serialize)]
@@ -245,6 +246,7 @@ pub enum InfixOp {
     Sub,
     Div,
     Mul,
+    Concat,
     LessThan,
 }
 
@@ -256,6 +258,7 @@ impl From<TokenKind> for InfixOp {
             TokenKind::Asterisk => Self::Mul,
             TokenKind::Slash => Self::Div,
             TokenKind::LessThan => Self::LessThan,
+            TokenKind::Dot => Self::Concat,
             _ => unreachable!()
         }
     }

trunk_parser/src/parser/mod.rs

@@ -694,6 +694,7 @@ impl Parser {
             TokenKind::Variable(v) => Expression::Variable(v.to_string()),
             TokenKind::Int(i) => Expression::Int(*i),
             TokenKind::Identifier(i) => Expression::Identifier(i.to_string()),
+            TokenKind::ConstantString(s) => Expression::ConstantString(s.to_string()),
             TokenKind::LeftParen => {
                 self.next();
 
@@ -913,6 +914,7 @@ fn infix_binding_power(t: &TokenKind) -> Option<(u8, u8)> {
     Some(match t {
         TokenKind::Asterisk | TokenKind::Slash => (13, 14),
         TokenKind::Plus | TokenKind::Minus => (11, 12),
+        TokenKind::Dot => (11, 11),
         TokenKind::LessThan => (9, 10),
         TokenKind::Equals => (2, 1),
         _ => return None,
@@ -1054,6 +1056,21 @@ mod tests {
         ]);
     }
 
+    #[test]
+    fn concat() {
+        assert_ast("<?php 'foo' . 'bar' . 'baz';", &[
+            expr!(Expression::Infix(
+                Box::new(Expression::ConstantString("foo".into())),
+                InfixOp::Concat,
+                Box::new(Expression::Infix(
+                    Box::new(Expression::ConstantString("bar".into())),
+                    InfixOp::Concat,
+                    Box::new(Expression::ConstantString("baz".into())),
+                ))
+            ))
+        ]);
+    }
+
     #[test]
     fn empty_fn() {
         assert_ast("<?php function foo() {}", &[