Add styler option

spec/column_spec.cr

@@ -7,6 +7,7 @@ describe Tablo::Column do
     align_header: Tablo::Justify::Left,
     align_body: Tablo::Justify::Left,
     formatter: ->(n : Tablo::CellType) { "%.2f" % n.as(Int32) },
+    styler: ->(n : Tablo::CellType) { n.to_s },
     extractor: ->(n : Array(Tablo::CellType)) { n[0].as(Tablo::CellType) })
 
   describe "#initialize" do

spec/spec_helper.cr

@@ -131,6 +131,13 @@ def add_columns_ndf(t : Tablo::Table)
   t
 end
 
+def add_columns_ndfs(t : Tablo::Table)
+  t.add_column("N") { |n| n[0] }
+  t.add_column("Double") { |n| n[0].as(Number) * 2 }
+  t.add_column("Triple", formatter: ->(val : Tablo::CellType) { "%.2f" % val }, styler: ->(val : Tablo::CellType) { "\e[31m#{val}\e[0m" }) { |n| n[0].as(Number) * 3 }
+  t
+end
+
 def add_columns_ndn(t : Tablo::Table)
   t.add_column("N") { |n| n[0] }
   t.add_column("Double") { |n| n[0].as(Number) * 2 }

spec/table_spec.cr

@@ -616,6 +616,27 @@ describe "Tablo::Table" do
     end
     # <<<<< formatter parameter
 
+    # >>>>> styler parameter
+    describe "`styler` param" do
+      it "styles the formatted cell value for display, without affecting the width calculations" do
+        t13a = add_columns_ndfs(mktable_5i32(default_header_alignment: Tablo::Justify::Center))
+        t13a.to_s.should eq \
+          %(+--------------+--------------+--------------+
+         |       N      |    Double    |    Triple    |
+         +--------------+--------------+--------------+
+         |            1 |            2 |         \e[31m3.00\e[0m |
+         |            2 |            4 |         \e[31m6.00\e[0m |
+         |            3 |            6 |         \e[31m9.00\e[0m |
+         |            4 |            8 |        \e[31m12.00\e[0m |
+         |            5 |           10 |        \e[31m15.00\e[0m |
+         +--------------+--------------+--------------+).gsub(/^ +/m, "")
+        top_right_body_cell = t13a.first.to_a.last
+        top_right_body_cell.should eq(3)
+        top_right_body_cell.should be_a(Int32)
+      end
+    end
+    # <<<<< styler parameter
+
     # >>>>> extractor parameter
     describe "'extractor' parameter is mandatory and must be provided as a block" do
       t14a = add_columns_5n(mktable_5i32(default_header_alignment: Tablo::Justify::Center))

src/column.cr

@@ -8,6 +8,7 @@ module Tablo
                    @align_header : Justify,
                    @align_body : Justify,
                    @formatter : CellType -> String,
+                   @styler : CellType -> String,
                    @extractor : Array(CellType) -> CellType)
     end
 
@@ -25,7 +26,7 @@ module Tablo
       type_alignment = infer_alignment(cell_datum) # Compute alignment from cell type
       @align_header = type_alignment if @align_header.none?
       @align_body = type_alignment if @align_body.none?
-      infilled_subcells(formatted_content, @align_body)
+      infilled_subcells(formatted_content, @align_body, true)
     end
 
     # Format the cell using the formatter proc
@@ -40,17 +41,23 @@ module Tablo
 
     # Calculates the number of lines necessary to deal with cell contents and
     # column width, and fills each resulting subcell with aligned data
-    private def infilled_subcells(str, alignment)
+    private def infilled_subcells(str, alignment, apply_styler = false)
       str.split("\n").flat_map do |substr|
         num_subsubcells = [1, (substr.size.to_f / width).ceil].max
         (0...num_subsubcells).map do |i|
-          align_cell_content(substr[i * width, width], alignment)
+          align_cell_content(substr[i * width, width], alignment, apply_styler)
         end
       end
     end
 
     # Calculate alignment and padding of a (sub)cell
-    private def align_cell_content(content, alignment)
+    private def align_cell_content(content, alignment, apply_styler)
+      styled_content =
+        if apply_styler
+          @styler.call(content)
+        else
+          content
+        end
       padding = [width - content.size, 0].max
       left_padding, right_padding =
         case alignment
@@ -62,7 +69,7 @@ module Tablo
           half_padding = padding // 2
           [padding - half_padding, half_padding]
         end
-      "#{" " * left_padding}#{content}#{" " * right_padding}"
+      "#{" " * left_padding}#{styled_content}#{" " * right_padding}"
     end
 
     # Calculate alignment of a (sub)cell

src/table.cr

@@ -56,6 +56,7 @@ module Tablo
     def add_column(label, header = nil, align_header = Justify::None,
                    align_body = Justify::None, width = nil,
                    formatter : CellType -> String = ->(n : CellType) { n.to_s },
+                   styler : CellType -> String = ->(n : CellType) { n.to_s },
                    &extractor : Array(CellType) -> CellType)
       if column_registry.has_key?(label)
         raise InvalidColumnLabelError.new("Column label already used in this table.")
@@ -67,6 +68,7 @@ module Tablo
         align_header,
         align_body,
         formatter,
+        styler,
         extractor
       )
     end