From 8856d733ad79b54294a6f3334bce7af785226abd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Emmanuel=20Beno=C3=AEt?= <tseeker@nocternity.net>
Date: Fri, 30 Dec 2022 23:50:02 +0100
Subject: [PATCH] AST - Expression node + dumper trait
---
src/ast.rs | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++
src/main.rs | 1 +
2 files changed, 56 insertions(+)
create mode 100644 src/ast.rs
diff --git a/src/ast.rs b/src/ast.rs
new file mode 100644
index 0000000..62080b2
--- /dev/null
+++ b/src/ast.rs
@@ -0,0 +1,55 @@
+use crate::tokens::{Token, TokenType};
+
+/// This trait should be implemented by nodes to allow AST dumps.
+pub trait AstDumper {
+ /// Dump the node as a string.
+ fn dump(&self) -> String;
+}
+
+/// An AST node that represents an expression.
+#[derive(Debug, Clone)]
+pub enum ExprNode {
+ /// Binary expression.
+ Binary {
+ left: Box<ExprNode>,
+ operator: Token,
+ right: Box<ExprNode>,
+ },
+
+ /// Unary expression.
+ Unary {
+ operator: Token,
+ right: Box<ExprNode>,
+ },
+
+ /// Grouping expression, containing a sub-expression.
+ Grouping { expression: Box<ExprNode> },
+
+ /// A litteral value, represented by the corresponding token.
+ Litteral { value: Token },
+}
+
+impl AstDumper for ExprNode {
+ fn dump(&self) -> String {
+ match self {
+ Self::Binary {
+ left,
+ operator,
+ right,
+ } => {
+ format!("( {} {} {} )", operator.lexeme, left.dump(), right.dump())
+ }
+ Self::Unary { operator, right } => {
+ format!("( {} {} )", operator.lexeme, right.dump())
+ }
+ Self::Grouping { expression } => {
+ format!("( {} )", expression.dump())
+ }
+ Self::Litteral { value } => match &value.token_type {
+ TokenType::String(s) => s.clone(),
+ TokenType::Number(n) => format!("{n}"),
+ _ => panic!("Unexpected token type for token {:#?}", value),
+ },
+ }
+ }
+}
diff --git a/src/main.rs b/src/main.rs
index e737b91..fe00d16 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,3 +1,4 @@
+mod ast;
mod errors;
mod scanner;
mod tokens;