lab1: language

Signed-off-by: Runji Wang <[email protected]>

Author: wangrunji0408

.gitignore

@@ -0,0 +1 @@
+/target

Cargo.lock

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+[package]
+name = "egg-sql-labs"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+egg = "0.9"

Cargo.toml

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+use egg::{define_language, Id, Symbol};
+
+mod value;
+
+pub use value::*;
+
+pub type RecExpr = egg::RecExpr<Expr>;
+
+define_language! {
+    pub enum Expr {
+        // values
+        Constant(Value),            // null, true, 1, 'hello'
+        Column(Symbol),             // t.a, b, c
+
+        // utilities
+        "list" = List(Box<[Id]>),   // (list ...)
+
+        // unary operations
+        "-" = Neg(Id),
+        "not" = Not(Id),
+        "isnull" = IsNull(Id),
+
+        // binary operations
+        "+" = Add([Id; 2]),
+        "-" = Sub([Id; 2]),
+        "*" = Mul([Id; 2]),
+        "/" = Div([Id; 2]),
+        "=" = Eq([Id; 2]),
+        "<>" = NotEq([Id; 2]),
+        ">" = Gt([Id; 2]),
+        "<" = Lt([Id; 2]),
+        ">=" = GtEq([Id; 2]),
+        "<=" = LtEq([Id; 2]),
+        "and" = And([Id; 2]),
+        "or" = Or([Id; 2]),
+        "xor" = Xor([Id; 2]),
+    }
+}

src/lib.rs

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+fn main() {
+    println!("Hello, world!");
+}

src/main.rs

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+use std::{fmt::Display, str::FromStr};
+
+/// SQL value.
+///
+/// # Display and Parse Format
+///
+/// - Null: `null`
+/// - Bool: `false`
+/// - Integer: `1`
+/// - String: `'string'`
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum Value {
+    Null,
+    Bool(bool),
+    Int(i32),
+    String(String),
+}
+
+impl Display for Value {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Value::Null => write!(f, "null"),
+            Value::Bool(b) => write!(f, "{b}"),
+            Value::Int(i) => write!(f, "{i}"),
+            Value::String(s) => write!(f, "'{s}'"),
+        }
+    }
+}
+
+impl FromStr for Value {
+    type Err = String;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        if s == "null" {
+            return Ok(Value::Null);
+        } else if let Ok(i) = s.parse() {
+            return Ok(Value::Bool(i));
+        } else if let Ok(i) = s.parse() {
+            return Ok(Value::Int(i));
+        } else if s.starts_with('\'') && s.ends_with('\'') {
+            return Ok(Value::String(s[1..s.len() - 1].to_string()));
+        }
+        Err(s.to_string())
+    }
+}

src/value.rs

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+use egg_sql_labs::{Expr, RecExpr, Value};
+
+#[test]
+fn values() {
+    assert_parse_value("null", Value::Null);
+    assert_parse_value("true", Value::Bool(true));
+    assert_parse_value("1", Value::Int(1));
+    assert_parse_value("'string'", Value::String("string".into()));
+}
+
+#[test]
+fn columns() {
+    assert_parse_expr("a");
+    assert_parse_expr("t.a");
+}
+
+#[test]
+fn list() {
+    assert_parse_expr("(list null 1 2)");
+}
+
+#[test]
+fn operations() {
+    assert_parse_expr("(isnull null)");
+    assert_parse_expr("(- a)");
+    assert_parse_expr("(+ a b)");
+    assert_parse_expr("(- a b)");
+    assert_parse_expr("(* a b)");
+    assert_parse_expr("(/ a b)");
+    assert_parse_expr("(= a b)");
+    assert_parse_expr("(<> a b)");
+    assert_parse_expr("(> a b)");
+    assert_parse_expr("(< a b)");
+    assert_parse_expr("(>= a b)");
+    assert_parse_expr("(<= a b)");
+    assert_parse_expr("(not a)");
+    assert_parse_expr("(and a b)");
+    assert_parse_expr("(or a b)");
+    assert_parse_expr("(xor a b)");
+}
+
+#[track_caller]
+fn assert_parse_value(expr: &str, value: Value) {
+    assert_eq!(
+        expr.parse::<RecExpr>().unwrap()[0.into()],
+        Expr::Constant(value)
+    );
+}
+
+#[track_caller]
+fn assert_parse_expr(expr: &str) {
+    assert_eq!(expr.parse::<RecExpr>().unwrap().to_string(), expr);
+}