Switch more commands to redirecting blocks (#956)

crates/nu-command/src/core_commands/for_.rs

@@ -1,4 +1,4 @@
-use nu_engine::{eval_block, eval_expression, CallExt};
+use nu_engine::{eval_block_with_redirect, eval_expression, CallExt};
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{CaptureBlock, Command, EngineState, Stack};
 use nu_protocol::{
@@ -99,7 +99,12 @@ impl Command for For {
                     );
 
                     //let block = engine_state.get_block(block_id);
-                    match eval_block(&engine_state, &mut stack, &block, PipelineData::new(head)) {
+                    match eval_block_with_redirect(
+                        &engine_state,
+                        &mut stack,
+                        &block,
+                        PipelineData::new(head),
+                    ) {
                         Ok(pipeline_data) => pipeline_data.into_value(head),
                         Err(error) => Value::Error { error },
                     }
@@ -131,7 +136,12 @@ impl Command for For {
                     );
 
                     //let block = engine_state.get_block(block_id);
-                    match eval_block(&engine_state, &mut stack, &block, PipelineData::new(head)) {
+                    match eval_block_with_redirect(
+                        &engine_state,
+                        &mut stack,
+                        &block,
+                        PipelineData::new(head),
+                    ) {
                         Ok(pipeline_data) => pipeline_data.into_value(head),
                         Err(error) => Value::Error { error },
                     }
@@ -140,7 +150,7 @@ impl Command for For {
             x => {
                 stack.add_var(var_id, x);
 
-                eval_block(&engine_state, &mut stack, &block, PipelineData::new(head))
+                eval_block_with_redirect(&engine_state, &mut stack, &block, PipelineData::new(head))
             }
         }
     }

crates/nu-command/src/filters/each.rs

@@ -1,4 +1,4 @@
-use nu_engine::{eval_block, CallExt};
+use nu_engine::{eval_block_with_redirect, CallExt};
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{CaptureBlock, Command, EngineState, Stack};
 use nu_protocol::{
@@ -105,7 +105,12 @@ impl Command for Each {
                         }
                     }
 
-                    match eval_block(&engine_state, &mut stack, &block, PipelineData::new(span)) {
+                    match eval_block_with_redirect(
+                        &engine_state,
+                        &mut stack,
+                        &block,
+                        PipelineData::new(span),
+                    ) {
                         Ok(v) => v.into_value(span),
                         Err(error) => Value::Error { error },
                     }
@@ -145,7 +150,12 @@ impl Command for Each {
                         }
                     }
 
-                    match eval_block(&engine_state, &mut stack, &block, PipelineData::new(span)) {
+                    match eval_block_with_redirect(
+                        &engine_state,
+                        &mut stack,
+                        &block,
+                        PipelineData::new(span),
+                    ) {
                         Ok(v) => v.into_value(span),
                         Err(error) => Value::Error { error },
                     }
@@ -179,7 +189,12 @@ impl Command for Each {
                         }
                     }
 
-                    match eval_block(&engine_state, &mut stack, &block, PipelineData::new(span))? {
+                    match eval_block_with_redirect(
+                        &engine_state,
+                        &mut stack,
+                        &block,
+                        PipelineData::new(span),
+                    )? {
                         PipelineData::Value(
                             Value::Record {
                                 mut cols, mut vals, ..
@@ -213,7 +228,7 @@ impl Command for Each {
                     }
                 }
 
-                eval_block(&engine_state, &mut stack, &block, PipelineData::new(span))
+                eval_block_with_redirect(&engine_state, &mut stack, &block, PipelineData::new(span))
             }
         }
     }

crates/nu-command/src/filters/each_group.rs

@@ -1,4 +1,4 @@
-use nu_engine::{eval_block, CallExt};
+use nu_engine::{eval_block_with_redirect, CallExt};
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{CaptureBlock, Command, EngineState, Stack};
 use nu_protocol::{
@@ -142,7 +142,7 @@ pub(crate) fn run_block_on_vec(
         }
     }
 
-    match eval_block(&engine_state, &mut stack, block, PipelineData::new(span)) {
+    match eval_block_with_redirect(&engine_state, &mut stack, block, PipelineData::new(span)) {
         Ok(pipeline) => pipeline,
         Err(error) => Value::Error { error }.into_pipeline_data(),
     }

crates/nu-command/src/filters/par_each.rs

@@ -1,4 +1,4 @@
-use nu_engine::{eval_block, CallExt};
+use nu_engine::{eval_block_with_redirect, CallExt};
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{CaptureBlock, Command, EngineState, Stack};
 use nu_protocol::{
@@ -87,7 +87,12 @@ impl Command for ParEach {
                         }
                     }
 
-                    match eval_block(&engine_state, &mut stack, block, PipelineData::new(span)) {
+                    match eval_block_with_redirect(
+                        &engine_state,
+                        &mut stack,
+                        block,
+                        PipelineData::new(span),
+                    ) {
                         Ok(v) => v,
                         Err(error) => Value::Error { error }.into_pipeline_data(),
                     }
@@ -128,7 +133,12 @@ impl Command for ParEach {
                         }
                     }
 
-                    match eval_block(&engine_state, &mut stack, block, PipelineData::new(span)) {
+                    match eval_block_with_redirect(
+                        &engine_state,
+                        &mut stack,
+                        block,
+                        PipelineData::new(span),
+                    ) {
                         Ok(v) => v,
                         Err(error) => Value::Error { error }.into_pipeline_data(),
                     }
@@ -168,7 +178,12 @@ impl Command for ParEach {
                         }
                     }
 
-                    match eval_block(&engine_state, &mut stack, block, PipelineData::new(span)) {
+                    match eval_block_with_redirect(
+                        &engine_state,
+                        &mut stack,
+                        block,
+                        PipelineData::new(span),
+                    ) {
                         Ok(v) => v,
                         Err(error) => Value::Error { error }.into_pipeline_data(),
                     }
@@ -213,7 +228,12 @@ impl Command for ParEach {
                         }
                     }
 
-                    match eval_block(&engine_state, &mut stack, block, PipelineData::new(span)) {
+                    match eval_block_with_redirect(
+                        &engine_state,
+                        &mut stack,
+                        block,
+                        PipelineData::new(span),
+                    ) {
                         Ok(v) => v,
                         Err(error) => Value::Error { error }.into_pipeline_data(),
                     }
@@ -250,7 +270,12 @@ impl Command for ParEach {
                         }
                     }
 
-                    match eval_block(&engine_state, &mut stack, block, PipelineData::new(span))? {
+                    match eval_block_with_redirect(
+                        &engine_state,
+                        &mut stack,
+                        block,
+                        PipelineData::new(span),
+                    )? {
                         PipelineData::Value(
                             Value::Record {
                                 mut cols, mut vals, ..
@@ -284,7 +309,7 @@ impl Command for ParEach {
                     }
                 }
 
-                eval_block(&engine_state, &mut stack, block, PipelineData::new(span))
+                eval_block_with_redirect(&engine_state, &mut stack, block, PipelineData::new(span))
             }
         }
     }

crates/nu-command/src/filters/where_.rs

@@ -1,4 +1,4 @@
-use nu_engine::{eval_block, CallExt};
+use nu_engine::{eval_block_with_redirect, CallExt};
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{CaptureBlock, Command, EngineState, Stack};
 use nu_protocol::{Category, PipelineData, Signature, SyntaxShape};
@@ -47,8 +47,12 @@ impl Command for Where {
                             stack.add_var(*var_id, value.clone());
                         }
                     }
-                    let result =
+                    let result = eval_block_with_redirect(
-                        eval_block(&engine_state, &mut stack, &block, PipelineData::new(span));
+                        &engine_state,
+                        &mut stack,
+                        &block,
+                        PipelineData::new(span),
+                    );
 
                     match result {
                         Ok(result) => result.into_value(span).is_true(),

crates/nu-engine/src/eval.rs

@@ -546,6 +546,80 @@ pub fn eval_block(
     Ok(input)
 }
 
+pub fn eval_block_with_redirect(
+    engine_state: &EngineState,
+    stack: &mut Stack,
+    block: &Block,
+    mut input: PipelineData,
+) -> Result<PipelineData, ShellError> {
+    let num_stmts = block.stmts.len();
+    for (stmt_idx, stmt) in block.stmts.iter().enumerate() {
+        if let Statement::Pipeline(pipeline) = stmt {
+            for elem in pipeline.expressions.iter() {
+                input = eval_expression_with_input(engine_state, stack, elem, input, false)?
+            }
+        }
+
+        if stmt_idx < (num_stmts) - 1 {
+            match input {
+                PipelineData::Value(Value::Nothing { .. }, ..) => {}
+                _ => {
+                    // Drain the input to the screen via tabular output
+                    let config = stack.get_config().unwrap_or_default();
+
+                    match engine_state.find_decl("table".as_bytes()) {
+                        Some(decl_id) => {
+                            let table = engine_state.get_decl(decl_id).run(
+                                engine_state,
+                                stack,
+                                &Call::new(Span::new(0, 0)),
+                                input,
+                            )?;
+
+                            for item in table {
+                                let stdout = std::io::stdout();
+
+                                if let Value::Error { error } = item {
+                                    return Err(error);
+                                }
+
+                                let mut out = item.into_string("\n", &config);
+                                out.push('\n');
+
+                                match stdout.lock().write_all(out.as_bytes()) {
+                                    Ok(_) => (),
+                                    Err(err) => eprintln!("{}", err),
+                                };
+                            }
+                        }
+                        None => {
+                            for item in input {
+                                let stdout = std::io::stdout();
+
+                                if let Value::Error { error } = item {
+                                    return Err(error);
+                                }
+
+                                let mut out = item.into_string("\n", &config);
+                                out.push('\n');
+
+                                match stdout.lock().write_all(out.as_bytes()) {
+                                    Ok(_) => (),
+                                    Err(err) => eprintln!("{}", err),
+                                };
+                            }
+                        }
+                    };
+                }
+            }
+
+            input = PipelineData::new(Span { start: 0, end: 0 })
+        }
+    }
+
+    Ok(input)
+}
+
 pub fn eval_subexpression(
     engine_state: &EngineState,
     stack: &mut Stack,

crates/nu-engine/src/lib.rs

@@ -10,6 +10,7 @@ pub use column::get_columns;
 pub use documentation::{generate_docs, get_brief_help, get_documentation, get_full_help};
 pub use env::*;
 pub use eval::{
-    eval_block, eval_expression, eval_expression_with_input, eval_operator, eval_subexpression,
+    eval_block, eval_block_with_redirect, eval_expression, eval_expression_with_input,
+    eval_operator, eval_subexpression,
 };
 pub use glob_from::glob_from;