string, glob interpolation

crates/nu-engine/src/compile/builder.rs

@@ -157,6 +157,11 @@ impl BlockBuilder {
                 decl_id: _,
                 src_dst: _,
             } => (),
+            Instruction::StringAppend { src_dst: _, val } => self.free_register(*val)?,
+            Instruction::GlobFrom {
+                src_dst: _,
+                no_expand: _,
+            } => (),
             Instruction::ListPush { src_dst: _, item } => self.free_register(*item)?,
             Instruction::ListSpread { src_dst: _, items } => self.free_register(*items)?,
             Instruction::RecordInsert {

crates/nu-engine/src/compile/error.rs

@@ -21,6 +21,7 @@ pub enum CompileError {
     RunExternalNotFound,
     InvalidLhsForAssignment(Span),
     ModifyImmutableVariable(Span),
+    UnexpectedExpr(&'static str),
     Todo(&'static str),
 }
 
@@ -56,6 +57,9 @@ impl CompileError {
             CompileError::ModifyImmutableVariable(_) => {
                 "attempted to modify immutable variable".into()
             }
+            CompileError::UnexpectedExpr(msg) => {
+                format!("unexpected expression in this context: {msg}")
+            }
             CompileError::Todo(msg) => {
                 format!("TODO: {msg}")
             }

crates/nu-engine/src/compile/expression.rs

@@ -6,8 +6,8 @@ use super::{
 use nu_protocol::{
     ast::{CellPath, Expr, Expression, ListItem, RecordItem},
     engine::StateWorkingSet,
-    ir::{Instruction, Literal},
+    ir::{DataSlice, Instruction, Literal},
-    IntoSpanned, RegId, ENV_VARIABLE_ID,
+    IntoSpanned, RegId, Type, ENV_VARIABLE_ID,
 };
 
 pub(crate) fn compile_expression(
@@ -124,7 +124,7 @@ pub(crate) fn compile_expression(
             )?;
             Ok(())
         }
-        Expr::VarDecl(_) => Err(CompileError::Todo("VarDecl")),
+        Expr::VarDecl(_) => Err(CompileError::UnexpectedExpr("VarDecl")),
         Expr::Call(call) => {
             move_in_reg_to_out_reg(builder)?;
 
@@ -135,7 +135,7 @@ pub(crate) fn compile_expression(
 
             compile_external_call(working_set, builder, head, args, redirect_modes, out_reg)
         }
-        Expr::Operator(_) => Err(CompileError::Todo("Operator")),
+        Expr::Operator(_) => Err(CompileError::UnexpectedExpr("Operator")),
         Expr::RowCondition(_) => Err(CompileError::Todo("RowCondition")),
         Expr::UnaryNot(subexpr) => {
             drop_input(builder)?;
@@ -354,7 +354,7 @@ pub(crate) fn compile_expression(
             }
             Ok(())
         }
-        Expr::Keyword(_) => Err(CompileError::Todo("Keyword")),
+        Expr::Keyword(_) => Err(CompileError::UnexpectedExpr("Keyword")),
         Expr::ValueWithUnit(_) => Err(CompileError::Todo("ValueWithUnit")),
         Expr::DateTime(_) => Err(CompileError::Todo("DateTime")),
         Expr::Filepath(path, no_expand) => {
@@ -430,8 +430,57 @@ pub(crate) fn compile_expression(
         Expr::ImportPattern(_) => Err(CompileError::Todo("ImportPattern")),
         Expr::Overlay(_) => Err(CompileError::Todo("Overlay")),
         Expr::Signature(_) => ignore(builder), // no effect
-        Expr::StringInterpolation(_) => Err(CompileError::Todo("StringInterpolation")),
+        Expr::StringInterpolation(exprs) | Expr::GlobInterpolation(exprs, _) => {
-        Expr::GlobInterpolation(_, _) => Err(CompileError::Todo("GlobInterpolation")),
+            let mut exprs_iter = exprs.iter().peekable();
+
+            if exprs_iter.peek().is_some_and(|e| e.ty == Type::String) {
+                // If the first expression is typed as a string, just take it and build from that
+                compile_expression(
+                    working_set,
+                    builder,
+                    exprs_iter.next().expect("peek() was Some"),
+                    redirect_modes.with_capture_out(expr.span),
+                    None,
+                    out_reg,
+                )?;
+            } else {
+                // Start with an empty string
+                lit(builder, Literal::String(DataSlice::empty()))?;
+            }
+
+            // Compile each expression and append to out_reg
+            for expr in exprs_iter {
+                let scratch_reg = builder.next_register()?;
+                compile_expression(
+                    working_set,
+                    builder,
+                    expr,
+                    redirect_modes.with_capture_out(expr.span),
+                    None,
+                    scratch_reg,
+                )?;
+                builder.push(
+                    Instruction::StringAppend {
+                        src_dst: out_reg,
+                        val: scratch_reg,
+                    }
+                    .into_spanned(expr.span),
+                )?;
+            }
+
+            // If it's a glob interpolation, change it to a glob
+            if let Expr::GlobInterpolation(_, no_expand) = expr.expr {
+                builder.push(
+                    Instruction::GlobFrom {
+                        src_dst: out_reg,
+                        no_expand,
+                    }
+                    .into_spanned(expr.span),
+                )?;
+            }
+
+            Ok(())
+        }
         Expr::Nothing => lit(builder, Literal::Nothing),
         Expr::Garbage => Err(CompileError::Garbage),
     }

crates/nu-engine/src/eval_ir.rs

@@ -299,6 +299,31 @@ fn eval_instruction(
             ctx.put_reg(*src_dst, result);
             Ok(Continue)
         }
+        Instruction::StringAppend { src_dst, val } => {
+            let string_value = ctx.collect_reg(*src_dst, *span)?;
+            let operand_value = ctx.collect_reg(*val, *span)?;
+            let string_span = string_value.span();
+
+            let mut string = string_value.into_string()?;
+            let operand = if let Value::String { val, .. } = operand_value {
+                // Small optimization, so we don't have to copy the string *again*
+                val
+            } else {
+                operand_value.to_expanded_string(", ", ctx.engine_state.get_config())
+            };
+            string.push_str(&operand);
+
+            let new_string_value = Value::string(string, string_span);
+            ctx.put_reg(*src_dst, new_string_value.into_pipeline_data());
+            Ok(Continue)
+        }
+        Instruction::GlobFrom { src_dst, no_expand } => {
+            let string_value = ctx.collect_reg(*src_dst, *span)?;
+            let string = string_value.into_string()?;
+            let glob_value = Value::glob(string, *no_expand, *span);
+            ctx.put_reg(*src_dst, glob_value.into_pipeline_data());
+            Ok(Continue)
+        }
         Instruction::ListPush { src_dst, item } => {
             let list_value = ctx.collect_reg(*src_dst, *span)?;
             let item = ctx.collect_reg(*item, *span)?;

crates/nu-protocol/src/ir/display.rs

@@ -115,6 +115,13 @@ impl<'a> fmt::Display for FmtInstruction<'a> {
                 let decl = FmtDecl::new(self.engine_state, *decl_id);
                 write!(f, "{:WIDTH$} {decl}, {src_dst}", "call")
             }
+            Instruction::StringAppend { src_dst, val } => {
+                write!(f, "{:WIDTH$} {src_dst}, {val}", "string-append")
+            }
+            Instruction::GlobFrom { src_dst, no_expand } => {
+                let no_expand = if *no_expand { "no-expand" } else { "expand" };
+                write!(f, "{:WIDTH$} {src_dst}, {no_expand}", "glob-from",)
+            }
             Instruction::ListPush { src_dst, item } => {
                 write!(f, "{:WIDTH$} {src_dst}, {item}", "list-push")
             }

crates/nu-protocol/src/ir/mod.rs

@@ -42,6 +42,13 @@ pub struct DataSlice {
     pub len: u32,
 }
 
+impl DataSlice {
+    /// A data slice that contains no data. This slice is always valid.
+    pub const fn empty() -> DataSlice {
+        DataSlice { start: 0, len: 0 }
+    }
+}
+
 impl std::ops::Index<DataSlice> for [u8] {
     type Output = [u8];
 
@@ -90,6 +97,11 @@ pub enum Instruction {
     /// Make a call. The input is taken from `src_dst`, and the output is placed in `src_dst`,
     /// overwriting it. The argument stack is used implicitly and cleared when the call ends.
     Call { decl_id: DeclId, src_dst: RegId },
+    /// Append a value onto the end of a string. Uses `to_expanded_string(", ", ...)` on the value.
+    /// Used for string interpolation literals. Not the same thing as the `++` operator.
+    StringAppend { src_dst: RegId, val: RegId },
+    /// Convert a string into a glob. Used for glob interpolation.
+    GlobFrom { src_dst: RegId, no_expand: bool },
     /// Push a value onto the end of a list. Used to construct list literals.
     ListPush { src_dst: RegId, item: RegId },
     /// Spread a value onto the end of a list. Used to construct list literals.