From a9252c5075916f9a43fec88800425c1bc14a8bfb Mon Sep 17 00:00:00 2001
From: Maxim Zhiburt <zhiburt@gmail.com>
Date: Sat, 10 May 2025 02:21:33 +0300
Subject: [PATCH] nu-table: (table --expand) Remove unnessary use of truncate
 logic (#15727)

A small optimization;

Must be measurable on large tables.
In case of `scope commands` for me seems like a bit faster in debug
(~100ms).
But I've had like a few runs.
If someone is interested to check if it's any faster would be nice to
see it :)

cc: @fdncred
---
 crates/nu-table/src/table.rs          | 34 +++++++++++++++++++--------
 crates/nu-table/src/types/expanded.rs |  6 ++---
 2 files changed, 27 insertions(+), 13 deletions(-)

diff --git a/crates/nu-table/src/table.rs b/crates/nu-table/src/table.rs
index 0300705c5f..8ebe165221 100644
--- a/crates/nu-table/src/table.rs
+++ b/crates/nu-table/src/table.rs
@@ -241,6 +241,13 @@ impl NuTable {
         build_table(self, termwidth)
     }
 
+    /// Converts a table to a String.
+    ///
+    /// It returns None in case where table cannot be fit to a terminal width.
+    pub fn draw_unchecked(self, termwidth: usize) -> Option<String> {
+        build_table_unchecked(self, termwidth)
+    }
+
     /// Return a total table width.
     pub fn total_width(&self) -> usize {
         let config = create_config(&self.config.theme, false, None);
@@ -327,6 +334,22 @@ impl HeadInfo {
     }
 }
 
+fn build_table_unchecked(mut t: NuTable, termwidth: usize) -> Option<String> {
+    if t.count_columns() == 0 || t.count_rows() == 0 {
+        return Some(String::new());
+    }
+
+    let widths = std::mem::take(&mut t.widths);
+    let config = create_config(&t.config.theme, false, None);
+    let totalwidth = get_total_width2(&t.widths, &config);
+    let widths = WidthEstimation::new(widths.clone(), widths, totalwidth, false, false);
+
+    let head = remove_header_if(&mut t);
+    table_insert_footer_if(&mut t);
+
+    draw_table(t, widths, head, termwidth)
+}
+
 fn build_table(mut t: NuTable, termwidth: usize) -> Option<String> {
     if t.count_columns() == 0 || t.count_rows() == 0 {
         return Some(String::new());
@@ -583,7 +606,7 @@ impl TableOption<NuRecords, ColoredConfig, CompleteDimensionVecRecords<'_>> for
         }
 
         // NOTE: just an optimization; to not recalculate it internally
-        SetDimensions(self.width.needed).change(recs, cfg, dims);
+        dims.set_widths(self.width.needed);
     }
 }
 
@@ -1021,15 +1044,6 @@ fn convert_alignment(alignment: nu_color_config::Alignment) -> AlignmentHorizont
     }
 }
 
-// TODO: expose it get_dims_mut()
-struct SetDimensions(Vec<usize>);
-
-impl<R> TableOption<R, ColoredConfig, CompleteDimensionVecRecords<'_>> for SetDimensions {
-    fn change(self, _: &mut R, _: &mut ColoredConfig, dims: &mut CompleteDimensionVecRecords<'_>) {
-        dims.set_widths(self.0);
-    }
-}
-
 fn build_width<R>(records: R, pad: usize) -> Vec<usize>
 where
     R: Records,
diff --git a/crates/nu-table/src/types/expanded.rs b/crates/nu-table/src/types/expanded.rs
index 52563efa3b..61e4b2069b 100644
--- a/crates/nu-table/src/types/expanded.rs
+++ b/crates/nu-table/src/types/expanded.rs
@@ -448,7 +448,7 @@ fn expand_value(value: &Value, width: usize, cfg: &Cfg<'_>) -> CellResult {
             match table {
                 Some(mut out) => {
                     table_apply_config(&mut out, cfg);
-                    let value = out.table.draw(width);
+                    let value = out.table.draw_unchecked(width);
                     match value {
                         Some(value) => Ok(Some(CellOutput::clean(value, out.count_rows, true))),
                         None => Ok(None),
@@ -556,7 +556,7 @@ fn expand_entry(item: &Value, cfg: Cfg<'_>) -> CellOutput {
 
             table_apply_config(&mut out, &cfg);
 
-            let table = out.table.draw(usize::MAX);
+            let table = out.table.draw_unchecked(cfg.opts.width);
             match table {
                 Some(table) => CellOutput::clean(table, out.count_rows, false),
                 None => {
@@ -622,7 +622,7 @@ fn maybe_expand_table(mut out: TableOutput, term_width: usize) -> StringResult {
         }
     }
 
-    let table = out.table.draw(term_width);
+    let table = out.table.draw_unchecked(term_width);
 
     Ok(table)
 }