Allow operator in constants (#10212)

This pr fixes https://github.com/nushell/nushell/issues/10200

# Description

Allow unary and binary operators in constants, e.g.

```bash
const a = 1 + 2
const b = [0, 1, 2, 3] ++ [4]
```

# User-Facing Changes

Now constants can contain operators.

# Tests + Formatting

- 🟢 `toolkit fmt`
- 🟢 `toolkit clippy`
- 🟢 `toolkit test`
- 🟢 `toolkit test stdlib`

# After Submitting

None

---------

Co-authored-by: Horasal <horsal@horsal.dev>

crates/nu-engine/src/eval.rs

@@ -2,8 +2,8 @@ use crate::{current_dir_str, get_full_help};
 use nu_path::expand_path_with;
 use nu_protocol::{
     ast::{
-        Argument, Assignment, Bits, Block, Boolean, Call, Comparison, Expr, Expression, Math,
-        Operator, PathMember, PipelineElement, Redirection,
+        eval_operator, Argument, Assignment, Bits, Block, Boolean, Call, Comparison, Expr,
+        Expression, Math, Operator, PathMember, PipelineElement, Redirection,
     },
     engine::{EngineState, ProfilingConfig, Stack},
     record, DataSource, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData,
@@ -13,19 +13,6 @@ use nu_protocol::{
 use std::collections::HashMap;
 use std::time::Instant;
 
-pub fn eval_operator(op: &Expression) -> Result<Operator, ShellError> {
-    match op {
-        Expression {
-            expr: Expr::Operator(operator),
-            ..
-        } => Ok(operator.clone()),
-        Expression { span, expr, .. } => Err(ShellError::UnknownOperator {
-            op_token: format!("{expr:?}"),
-            span: *span,
-        }),
-    }
-}
-
 pub fn eval_call(
     engine_state: &EngineState,
     caller_stack: &mut Stack,

crates/nu-engine/src/lib.rs

@@ -12,6 +12,6 @@ pub use documentation::get_full_help;
 pub use env::*;
 pub use eval::{
     eval_block, eval_block_with_early_return, eval_call, eval_expression,
-    eval_expression_with_input, eval_operator, eval_subexpression, eval_variable, redirect_env,
+    eval_expression_with_input, eval_subexpression, eval_variable, redirect_env,
 };
 pub use glob_from::glob_from;

crates/nu-protocol/src/ast/operator.rs

@@ -1,8 +1,10 @@
-use crate::Span;
+use crate::{ShellError, Span};
 
 use serde::{Deserialize, Serialize};
 use std::fmt::Display;
 
+use super::{Expr, Expression};
+
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 pub enum Comparison {
     Equal,
@@ -128,3 +130,16 @@ impl Display for RangeOperator {
         }
     }
 }
+
+pub fn eval_operator(op: &Expression) -> Result<Operator, ShellError> {
+    match op {
+        Expression {
+            expr: Expr::Operator(operator),
+            ..
+        } => Ok(operator.clone()),
+        Expression { span, expr, .. } => Err(ShellError::UnknownOperator {
+            op_token: format!("{expr:?}"),
+            span: *span,
+        }),
+    }
+}

crates/nu-protocol/src/eval_const.rs

@@ -1,7 +1,10 @@
 use crate::{
-    ast::{Block, Call, Expr, Expression, PipelineElement},
+    ast::{
+        eval_operator, Bits, Block, Boolean, Call, Comparison, Expr, Expression, Math, Operator,
+        PipelineElement,
+    },
     engine::{EngineState, StateWorkingSet},
-    record, HistoryFileFormat, PipelineData, Record, ShellError, Span, Value,
+    record, HistoryFileFormat, PipelineData, Range, Record, ShellError, Span, Value,
 };
 use nu_system::os_info::{get_kernel_version, get_os_arch, get_os_family, get_os_name};
 use std::path::PathBuf;
@@ -342,6 +345,132 @@ pub fn eval_constant(
                     .into_value(expr.span),
             )
         }
+        Expr::Range(from, next, to, operator) => {
+            let from = if let Some(f) = from {
+                eval_constant(working_set, f)?
+            } else {
+                Value::Nothing {
+                    internal_span: expr.span,
+                }
+            };
+
+            let next = if let Some(s) = next {
+                eval_constant(working_set, s)?
+            } else {
+                Value::Nothing {
+                    internal_span: expr.span,
+                }
+            };
+
+            let to = if let Some(t) = to {
+                eval_constant(working_set, t)?
+            } else {
+                Value::Nothing {
+                    internal_span: expr.span,
+                }
+            };
+            Ok(Value::Range {
+                val: Box::new(Range::new(expr.span, from, next, to, operator)?),
+                internal_span: expr.span,
+            })
+        }
+        Expr::UnaryNot(expr) => {
+            let lhs = eval_constant(working_set, expr)?;
+            match lhs {
+                Value::Bool { val, .. } => Ok(Value::bool(!val, expr.span)),
+                _ => Err(ShellError::TypeMismatch {
+                    err_message: "bool".to_string(),
+                    span: expr.span,
+                }),
+            }
+        }
+        Expr::BinaryOp(lhs, op, rhs) => {
+            let op_span = op.span;
+            let op = eval_operator(op)?;
+
+            match op {
+                Operator::Boolean(boolean) => {
+                    let lhs = eval_constant(working_set, lhs)?;
+                    match boolean {
+                        Boolean::And => {
+                            if lhs.is_false() {
+                                Ok(Value::bool(false, expr.span))
+                            } else {
+                                let rhs = eval_constant(working_set, rhs)?;
+                                lhs.and(op_span, &rhs, expr.span)
+                            }
+                        }
+                        Boolean::Or => {
+                            if lhs.is_true() {
+                                Ok(Value::bool(true, expr.span))
+                            } else {
+                                let rhs = eval_constant(working_set, rhs)?;
+                                lhs.or(op_span, &rhs, expr.span)
+                            }
+                        }
+                        Boolean::Xor => {
+                            let rhs = eval_constant(working_set, rhs)?;
+                            lhs.xor(op_span, &rhs, expr.span)
+                        }
+                    }
+                }
+                Operator::Math(math) => {
+                    match (&math, &lhs.expr, &rhs.expr) {
+                        // Multiple may generate super long string
+                        // and stop the whole shell while highlighting
+                        // e.g. '2 ** 60 * a'
+                        (Math::Multiply, Expr::String(..), _)
+                        | (Math::Multiply, _, Expr::String(..)) => {
+                            return Err(ShellError::NotAConstant(expr.span))
+                        }
+                        _ => {}
+                    }
+                    let lhs = eval_constant(working_set, lhs)?;
+                    let rhs = eval_constant(working_set, rhs)?;
+
+                    match math {
+                        Math::Plus => lhs.add(op_span, &rhs, expr.span),
+                        Math::Minus => lhs.sub(op_span, &rhs, expr.span),
+                        Math::Multiply => lhs.mul(op_span, &rhs, expr.span),
+                        Math::Divide => lhs.div(op_span, &rhs, expr.span),
+                        Math::Append => lhs.append(op_span, &rhs, expr.span),
+                        Math::Modulo => lhs.modulo(op_span, &rhs, expr.span),
+                        Math::FloorDivision => lhs.floor_div(op_span, &rhs, expr.span),
+                        Math::Pow => lhs.pow(op_span, &rhs, expr.span),
+                    }
+                }
+                Operator::Comparison(comparison) => {
+                    let lhs = eval_constant(working_set, lhs)?;
+                    let rhs = eval_constant(working_set, rhs)?;
+                    match comparison {
+                        Comparison::LessThan => lhs.lt(op_span, &rhs, expr.span),
+                        Comparison::LessThanOrEqual => lhs.lte(op_span, &rhs, expr.span),
+                        Comparison::GreaterThan => lhs.gt(op_span, &rhs, expr.span),
+                        Comparison::GreaterThanOrEqual => lhs.gte(op_span, &rhs, expr.span),
+                        Comparison::Equal => lhs.eq(op_span, &rhs, expr.span),
+                        Comparison::NotEqual => lhs.ne(op_span, &rhs, expr.span),
+                        Comparison::In => lhs.r#in(op_span, &rhs, expr.span),
+                        Comparison::NotIn => lhs.not_in(op_span, &rhs, expr.span),
+                        Comparison::StartsWith => lhs.starts_with(op_span, &rhs, expr.span),
+                        Comparison::EndsWith => lhs.ends_with(op_span, &rhs, expr.span),
+                        // RegEx comparison is not a constant
+                        _ => Err(ShellError::NotAConstant(expr.span)),
+                    }
+                }
+                Operator::Bits(bits) => {
+                    let lhs = eval_constant(working_set, lhs)?;
+                    let rhs = eval_constant(working_set, rhs)?;
+                    match bits {
+                        Bits::BitAnd => lhs.bit_and(op_span, &rhs, expr.span),
+                        Bits::BitOr => lhs.bit_or(op_span, &rhs, expr.span),
+                        Bits::BitXor => lhs.bit_xor(op_span, &rhs, expr.span),
+                        Bits::ShiftLeft => lhs.bit_shl(op_span, &rhs, expr.span),
+                        Bits::ShiftRight => lhs.bit_shr(op_span, &rhs, expr.span),
+                    }
+                }
+                Operator::Assignment(_) => Err(ShellError::NotAConstant(expr.span)),
+            }
+        }
         _ => Err(ShellError::NotAConstant(expr.span)),
     }
 }

tests/const_/mod.rs

@@ -1,5 +1,6 @@
 use nu_test_support::nu;
 use pretty_assertions::assert_eq;
+use rstest::rstest;
 
 const MODULE_SETUP: &str = r#"
     module spam {
@@ -107,6 +108,54 @@ fn const_nothing() {
     assert_eq!(actual.out, "nothing");
 }
 
+#[rstest]
+#[case(&["const x = not false", "$x"], "true")]
+#[case(&["const x = false", "const y = not $x", "$y"], "true")]
+#[case(&["const x = not false", "const y = not $x", "$y"], "false")]
+fn const_unary_operator(#[case] inp: &[&str], #[case] expect: &str) {
+    let actual = nu!(&inp.join("; "));
+    assert_eq!(actual.out, expect);
+}
+
+#[rstest]
+#[case(&["const x = 1 + 2", "$x"], "3")]
+#[case(&["const x = 1 * 2", "$x"], "2")]
+#[case(&["const x = 4 / 2", "$x"], "2")]
+#[case(&["const x = 4 mod 3", "$x"], "1")]
+#[case(&["const x = 5.0 / 2.0", "$x"], "2.5")]
+#[case(&[r#"const x = "a" + "b" "#, "$x"], "ab")]
+#[case(&[r#"const x = "a" ++ "b" "#, "$x"], "ab")]
+#[case(&[r#"const x = [1,2] ++ [3]"#, "$x | describe"], "list<int>")]
+#[case(&[r#"const x = 0x[1,2] ++ 0x[3]"#, "$x | describe"], "binary")]
+#[case(&[r#"const x = 0x[1,2] ++ [3]"#, "$x | describe"], "list<any>")]
+#[case(&["const x = 1 < 2", "$x"], "true")]
+#[case(&["const x = (3 * 200) > (2 * 100)", "$x"], "true")]
+#[case(&["const x = (3 * 200) < (2 * 100)", "$x"], "false")]
+#[case(&["const x = (3 * 200) == (2 * 300)", "$x"], "true")]
+fn const_binary_operator(#[case] inp: &[&str], #[case] expect: &str) {
+    let actual = nu!(&inp.join("; "));
+    assert_eq!(actual.out, expect);
+}
+
+#[rstest]
+#[case(&["const x = 1 / 0", "$x"], "division by zero")]
+#[case(&["const x = 10 ** 10000000", "$x"], "pow operation overflowed")]
+#[case(&["const x = 2 ** 62 * 2", "$x"], "multiply operation overflowed")]
+#[case(&["const x = 1 ++ 0", "$x"], "doesn't support this value")]
+#[case(&["const x = 20 * a", "$x"], "Value is not a parse-time constant")]
+fn const_operator_error(#[case] inp: &[&str], #[case] expect: &str) {
+    let actual = nu!(&inp.join("; "));
+    assert!(actual.err.contains(expect));
+}
+
+#[rstest]
+#[case(&["const x = (1..3)", "$x | math sum"], "6")]
+#[case(&["const x = (1..3)", "$x | describe"], "range")]
+fn const_range(#[case] inp: &[&str], #[case] expect: &str) {
+    let actual = nu!(&inp.join("; "));
+    assert_eq!(actual.out, expect);
+}
+
 #[test]
 fn const_subexpression_supported() {
     let inp = &["const x = ('spam')", "$x"];