Add search terms to Command and Signature (#4980)

* Add search terms to command

* Rename Signature desc to usage

To be named uniformly with extra_usage

* Throw in foldl search term for reduce

* Add missing usage to post

* Add search terms to signature

* Try to add capnp Signature serialization

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

@@ -17,7 +17,6 @@ impl Command for Do {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("do")
-            .desc(self.usage())
             .required("block", SyntaxShape::Any, "the block to run")
             .switch(
                 "ignore-errors",

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

@@ -7,6 +7,8 @@ use nu_protocol::{
 
 use nu_engine::{get_full_help, CallExt};
 
+use std::borrow::Borrow;
+
 #[derive(Clone)]
 pub struct Help;
 
@@ -96,14 +98,22 @@ fn help(
             let mut vals = vec![];
 
             let decl = engine_state.get_decl(decl_id);
-            let sig = decl.signature();
+            let sig = decl.signature().update_from_command(decl.borrow());
+
+            let key = sig.name;
+            let usage = sig.usage;
+            let search_terms = sig.search_terms;
+            let matches_term = if search_terms.is_empty() {
+                search_terms
+                    .iter()
+                    .any(|term| term.to_lowercase().contains(&search_string))
+            } else {
+                false
+            };
 
-            let key = sig.name.clone();
-            let c = sig.usage.clone();
-            let e = sig.extra_usage.clone();
             if key.to_lowercase().contains(&search_string)
-                || c.to_lowercase().contains(&search_string)
-                || e.to_lowercase().contains(&search_string)
+                || usage.to_lowercase().contains(&search_string)
+                || matches_term
             {
                 cols.push("name".into());
                 vals.push(Value::String {
@@ -136,10 +146,20 @@ fn help(
                 });
 
                 cols.push("usage".into());
-                vals.push(Value::String { val: c, span: head });
+                vals.push(Value::String {
+                    val: usage,
+                    span: head,
+                });
 
-                cols.push("extra_usage".into());
-                vals.push(Value::String { val: e, span: head });
+                cols.push("search_terms".into());
+                vals.push(if search_terms.is_empty() {
+                    Value::nothing(head)
+                } else {
+                    Value::String {
+                        val: search_terms.join(", "),
+                        span: head,
+                    }
+                });
 
                 found_cmds_vec.push(Value::Record {
                     cols,
@@ -163,11 +183,11 @@ fn help(
                 let mut vals = vec![];
 
                 let decl = engine_state.get_decl(decl_id);
-                let sig = decl.signature();
+                let sig = decl.signature().update_from_command(decl.borrow());
 
-                let key = sig.name.clone();
-                let c = sig.usage.clone();
-                let e = sig.extra_usage.clone();
+                let key = sig.name;
+                let usage = sig.usage;
+                let search_terms = sig.search_terms;
 
                 cols.push("name".into());
                 vals.push(Value::String {
@@ -200,10 +220,20 @@ fn help(
                 });
 
                 cols.push("usage".into());
-                vals.push(Value::String { val: c, span: head });
+                vals.push(Value::String {
+                    val: usage,
+                    span: head,
+                });
 
-                cols.push("extra_usage".into());
-                vals.push(Value::String { val: e, span: head });
+                cols.push("search_terms".into());
+                vals.push(if search_terms.is_empty() {
+                    Value::nothing(head)
+                } else {
+                    Value::String {
+                        val: search_terms.join(", "),
+                        span: head,
+                    }
+                });
 
                 found_cmds_vec.push(Value::Record {
                     cols,

crates/nu-command/src/experimental/view_source.rs

@@ -20,7 +20,6 @@ impl Command for ViewSource {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("view-source")
-            .desc(self.usage())
             .required("item", SyntaxShape::Any, "name or block to view")
             .category(Category::Core)
     }

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

@@ -36,6 +36,10 @@ impl Command for Reduce {
         "Aggregate a list table to a single value using an accumulator block."
     }
 
+    fn search_terms(&self) -> Vec<&str> {
+        vec!["map", "fold", "foldl"]
+    }
+
     fn examples(&self) -> Vec<Example> {
         vec![
             Example {

crates/nu-command/src/network/fetch.rs

@@ -27,7 +27,6 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("fetch")
-            .desc("Load from a URL into a cell, convert to table if possible (avoid by appending '--raw').")
             .required(
                 "URL",
                 SyntaxShape::String,
@@ -45,15 +44,33 @@ impl Command for SubCommand {
                 "the password when authenticating",
                 Some('p'),
             )
-            .named("timeout", SyntaxShape::Int, "timeout period in seconds", Some('t'))
-            .named("headers",SyntaxShape::Any, "custom headers you want to add ", Some('H'))
-            .switch("raw", "fetch contents as text rather than a table", Some('r'))
+            .named(
+                "timeout",
+                SyntaxShape::Int,
+                "timeout period in seconds",
+                Some('t'),
+            )
+            .named(
+                "headers",
+                SyntaxShape::Any,
+                "custom headers you want to add ",
+                Some('H'),
+            )
+            .switch(
+                "raw",
+                "fetch contents as text rather than a table",
+                Some('r'),
+            )
             .filter()
             .category(Category::Network)
     }
 
     fn usage(&self) -> &str {
-        "Fetch the contents from a URL (HTTP GET operation)."
+        "Fetch the contents from a URL."
+    }
+
+    fn extra_usage(&self) -> &str {
+        "Performs HTTP GET operation."
     }
 
     fn run(

crates/nu-command/src/network/post.rs

@@ -24,7 +24,6 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("post")
-            .desc("Post content to a URL and retrieve data as a table if possible.")
             .required("path", SyntaxShape::String, "the URL to post to")
             .required("body", SyntaxShape::Any, "the contents of the post body")
             .named(
@@ -70,9 +69,15 @@ impl Command for SubCommand {
             .filter()
             .category(Category::Network)
     }
+
     fn usage(&self) -> &str {
-        "Post a body to a URL (HTTP POST operation)."
+        "Post a body to a URL."
     }
+
+    fn extra_usage(&self) -> &str {
+        "Performs HTTP POST operation."
+    }
+
     fn run(
         &self,
         engine_state: &EngineState,

crates/nu-command/src/system/ps.rs

@@ -16,7 +16,6 @@ impl Command for Ps {
 
     fn signature(&self) -> Signature {
         Signature::build("ps")
-            .desc("View information about system processes.")
             .switch(
                 "long",
                 "list all available columns for each entry",

crates/nu-command/src/system/sys.rs

@@ -14,10 +14,7 @@ impl Command for Sys {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("sys")
-            .desc("View information about the current system.")
-            .filter()
-            .category(Category::System)
+        Signature::build("sys").filter().category(Category::System)
     }
 
     fn usage(&self) -> &str {