Fix it expansion and add collect (#2065)

crates/nu-cli/src/cli.rs

@@ -303,6 +303,7 @@ pub fn create_default_context(
             whole_stream_command(StrSet),
             whole_stream_command(StrToDatetime),
             whole_stream_command(StrTrim),
+            whole_stream_command(StrCollect),
             whole_stream_command(BuildString),
             whole_stream_command(Ansi),
             // Column manipulation
@@ -657,10 +658,12 @@ pub async fn cli(
 
                 if let Ok(result) = nu_parser::lite_parse(&prompt_line, 0).map_err(ShellError::from)
                 {
-                    let prompt_block = nu_parser::classify_block(&result, context.registry());
+                    let mut prompt_block = nu_parser::classify_block(&result, context.registry());
 
                     let env = context.get_env();
 
+                    prompt_block.block.expand_it_usage();
+
                     match run_block(
                         &prompt_block.block,
                         &mut context,

crates/nu-cli/src/commands.rs

@@ -240,8 +240,8 @@ pub(crate) use split::SplitColumn;
 pub(crate) use split::SplitRow;
 pub(crate) use split_by::SplitBy;
 pub(crate) use str_::{
-    Str, StrCapitalize, StrDowncase, StrFindReplace, StrSet, StrSubstring, StrToDatetime,
-    StrToDecimal, StrToInteger, StrTrim, StrUpcase,
+    Str, StrCapitalize, StrCollect, StrDowncase, StrFindReplace, StrSet, StrSubstring,
+    StrToDatetime, StrToDecimal, StrToInteger, StrTrim, StrUpcase,
 };
 #[allow(unused_imports)]
 pub(crate) use t_sort_by::TSortBy;

crates/nu-cli/src/commands/str_/collect.rs

@@ -0,0 +1,56 @@
+use crate::commands::WholeStreamCommand;
+use crate::prelude::*;
+use nu_errors::ShellError;
+use nu_protocol::{ReturnSuccess, Signature, UntaggedValue, Value};
+
+pub struct SubCommand;
+
+#[async_trait]
+impl WholeStreamCommand for SubCommand {
+    fn name(&self) -> &str {
+        "str collect"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("str collect")
+    }
+
+    fn usage(&self) -> &str {
+        "collects a list of strings into a string"
+    }
+
+    async fn run(
+        &self,
+        args: CommandArgs,
+        _registry: &CommandRegistry,
+    ) -> Result<OutputStream, ShellError> {
+        let output = args
+            .input
+            .collect_string(args.call_info.name_tag.clone())
+            .await?;
+
+        Ok(OutputStream::one(ReturnSuccess::value(
+            UntaggedValue::string(output.item).into_value(output.tag),
+        )))
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![Example {
+            description: "Collect a list of string",
+            example: "echo ['a' 'b' 'c'] | str collect",
+            result: Some(vec![Value::from("abc")]),
+        }]
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::SubCommand;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(SubCommand {})
+    }
+}

crates/nu-cli/src/commands/str_/mod.rs

@@ -1,4 +1,5 @@
 mod capitalize;
+mod collect;
 mod command;
 mod downcase;
 mod find_replace;
@@ -11,6 +12,7 @@ mod trim;
 mod upcase;
 
 pub use capitalize::SubCommand as StrCapitalize;
+pub use collect::SubCommand as StrCollect;
 pub use command::Command as Str;
 pub use downcase::SubCommand as StrDowncase;
 pub use find_replace::SubCommand as StrFindReplace;

crates/nu-cli/src/stream/input.rs

@@ -1,7 +1,7 @@
 use crate::prelude::*;
 use futures::stream::{iter, once};
 use nu_errors::ShellError;
-use nu_protocol::{Primitive, UntaggedValue, Value};
+use nu_protocol::{Primitive, Type, UntaggedValue, Value};
 use nu_source::{Tagged, TaggedItem};
 
 pub struct InputStream {
@@ -74,12 +74,18 @@ impl InputStream {
                     value_tag = value_t;
                     bytes.extend_from_slice(&b);
                 }
-                Some(Value { tag: value_tag, .. }) => {
+                Some(Value {
+                    tag: value_tag,
+                    value,
+                }) => {
                     return Err(ShellError::labeled_error_with_secondary(
                         "Expected a string from pipeline",
                         "requires string input",
                         tag,
-                        "value originates from here",
+                        format!(
+                            "{} originates from here",
+                            Type::from_value(&value).plain_string(100000)
+                        ),
                         value_tag,
                     ))
                 }

crates/nu-protocol/src/hir.rs

@@ -44,6 +44,14 @@ impl InternalCommand {
             ),
         }
     }
+
+    pub fn expand_it_usage(&mut self) {
+        if let Some(positionals) = &mut self.args.positional {
+            for arg in positionals {
+                arg.expand_it_usage();
+            }
+        }
+    }
 }
 
 #[derive(Debug, Clone, PartialEq, PartialOrd, Eq, Ord, Hash, Serialize, Deserialize)]
@@ -109,34 +117,8 @@ impl ClassifiedCommand {
 
     pub fn expand_it_usage(&mut self) {
         match self {
-            ClassifiedCommand::Internal(command) => {
-                if let Some(positionals) = &mut command.args.positional {
-                    for arg in positionals {
-                        if let SpannedExpression {
-                            expr: Expression::Block(block),
-                            ..
-                        } = arg
-                        {
-                            block.expand_it_usage();
-                        }
-                    }
-                }
-            }
-            ClassifiedCommand::Expr(expr) => {
-                if let SpannedExpression {
-                    expr: Expression::Block(ref block),
-                    span,
-                } = **expr
-                {
-                    let mut block = block.clone();
-                    block.expand_it_usage();
-                    *expr = Box::new(SpannedExpression {
-                        expr: Expression::Block(block),
-                        span,
-                    });
-                }
-            }
-
+            ClassifiedCommand::Internal(command) => command.expand_it_usage(),
+            ClassifiedCommand::Expr(expr) => expr.expand_it_usage(),
             _ => {}
         }
     }
@@ -588,6 +570,44 @@ impl SpannedExpression {
             _ => false,
         }
     }
+
+    pub fn expand_it_usage(&mut self) {
+        match self {
+            SpannedExpression {
+                expr: Expression::Block(block),
+                ..
+            } => {
+                block.expand_it_usage();
+            }
+            SpannedExpression {
+                expr: Expression::Invocation(block),
+                ..
+            } => {
+                block.expand_it_usage();
+            }
+            SpannedExpression {
+                expr: Expression::List(list),
+                ..
+            } => {
+                for item in list.iter_mut() {
+                    item.expand_it_usage();
+                }
+            }
+            SpannedExpression {
+                expr: Expression::Path(path),
+                ..
+            } => {
+                if let SpannedExpression {
+                    expr: Expression::Invocation(block),
+                    ..
+                } = &mut path.head
+                {
+                    block.expand_it_usage();
+                }
+            }
+            _ => {}
+        }
+    }
 }
 
 impl std::ops::Deref for SpannedExpression {

tests/shell/pipeline/commands/internal.rs

@@ -72,6 +72,18 @@ fn it_expansion_of_list() {
     assert_eq!(actual.out, "[\"bar\",\"foo\"]");
 }
 
+#[test]
+fn it_expansion_of_invocation() {
+    let actual = nu!(
+        cwd: ".",
+        r#"
+            echo $(echo "4" | echo $it | str to-int )
+        "#
+    );
+
+    assert_eq!(actual.out, "4");
+}
+
 #[test]
 fn argument_invocation() {
     let actual = nu!(