feat: support eliding padding in header separator (#17)

Closes #16

Author: haltcase

readme.md

@@ -37,11 +37,13 @@ tablemark([
 
 ... displays as:
 
+<!-- prettier-ignore-start -->
 | Name  | Age   | Is cool |
 | :---- | :---- | :------ |
 | Bob   | 21    | false   |
 | Sarah | 22    | true    |
 | Lee   | 23    | true    |
+<!-- prettier-ignore-end -->
 
 ## api
 
@@ -55,14 +57,15 @@ tablemark (input: InputData, options?: TablemarkOptions): string
   * an array of objects or iterables
 * `TablemarkOptions` options:
 
-  | key            | type         | default    | description                                    |
-  | :------------: | :----------: | :--------: | ---------------------------------------------- |
-  | `columns`      | `Array<string \| ColumnDescriptor>` | - | Array of column descriptors.                    |
-  | `caseHeaders`  | `boolean`    | `true`     | Sentence case headers derived from keys.       |
-  | `toCellText`    | `(input: unknown) => string` | - | Provide a custom "toString" function.       |
-  | `wrapWidth`   | `number`     | `Infinity` | Wrap cell text at this length.                     |
-  | `wrapWithGutters` | `boolean`    | `false`    | Add sides (`\| <content> \|`) to wrapped rows. |
-  | `lineEnding` | `string` | `"\n"` | String used at end-of-line. |
+  |         key          |                type                 |  default   | description                                                     |
+  | :------------------: | :---------------------------------: | :--------: | --------------------------------------------------------------- |
+  |      `columns`       | `Array<string \| ColumnDescriptor>` |     -      | Array of column descriptors.                                    |
+  |    `caseHeaders`     |              `boolean`              |   `true`   | Sentence case headers derived from keys.                        |
+  |     `toCellText`     |    `(input: unknown) => string`     |     -      | Provide a custom "toString" function.                           |
+  | `padHeaderSeparator` |              `boolean`              |   `true`   | Whether to pad gutters of the header separator (alignment) row. |
+  |     `wrapWidth`      |              `number`               | `Infinity` | Wrap cell text at this length.                                  |
+  |  `wrapWithGutters`   |              `boolean`              |  `false`   | Add sides (`\| <content> \|`) to wrapped rows.                  |
+  |     `lineEnding`     |              `string`               |   `"\n"`   | String used at end-of-line.                                     |
 
 The `columns` array can either contain objects, in which case their
 `name` and `align` properties will be used to alter the display of
@@ -103,11 +106,44 @@ tablemark([
 
 ... displays as:
 
+<!-- prettier-ignore-start -->
 | first name | how old | are they cool |
 | :--------- | :-----: | :------------ |
 | Bob        |   21    | false         |
 | Sarah      |   22    | true          |
 | Lee        |   23    | true          |
+<!-- prettier-ignore-end -->
+
+### `options.padHeaderSeparator`
+
+```js
+tablemark(
+  [
+    { name: "Bob", age: 21, isCool: false },
+    { name: "Sarah", age: 22, isCool: true },
+    { name: "Lee", age: 23, isCool: true }
+  ],
+  {
+    columns: [{ align: "left" }, { align: "center" }, { align: "right" }]
+  }
+)
+
+// | first name | how old | are they cool |
+// |:-----------|:-------:|--------------:|
+// | Bob        |   21    | false         |
+// | Sarah      |   22    | true          |
+// | Lee        |   23    | true          |
+```
+
+... displays as:
+
+<!-- prettier-ignore-start -->
+| first name | how old | are they cool |
+|:-----------|:-------:|--------------:|
+| Bob        |   21    | false         |
+| Sarah      |   22    | true          |
+| Lee        |   23    | true          |
+<!-- prettier-ignore-end -->
 
 ### `options.toCellText`
 

src/index.ts

@@ -32,20 +32,25 @@ export default (input: InputData, options: TablemarkOptions = {}): string => {
   // header line
   table += row(alignments, widths, titles, config)
 
+  const dashLengthOffset = config.padHeaderSeparator ? 2 : 0
+
   // header separator
   table += line(
     alignments.map(
       (align, i) =>
         (align === alignmentOptions.left || align === alignmentOptions.center
           ? ":"
           : "-") +
-        "-".repeat(widths[i] - 2) +
+        "-".repeat(widths[i] - dashLengthOffset) +
         (align === alignmentOptions.right || align === alignmentOptions.center
           ? ":"
           : "-")
     ),
     config,
-    true
+    {
+      forceGutters: true,
+      isHeaderSeparator: true
+    }
   )
 
   // table body

src/types.ts

@@ -63,6 +63,11 @@ export interface TablemarkOptions {
    * Text to use as the line ending, `\n` by default.
    */
   lineEnding?: string
+
+  /**
+   * Include padding on the header separator row, `true` by default.
+   */
+  padHeaderSeparator?: boolean
 }
 
 export type TablemarkOptionsNormalized = Omit<

src/utilities.ts

@@ -48,14 +48,25 @@ export const toCellText: ToCellText = v => {
 export const line = (
   columns: readonly string[],
   config: TablemarkOptionsNormalized,
-  forceGutters = false
+  {
+    forceGutters = false,
+    isHeaderSeparator = false
+  }: {
+    forceGutters?: boolean
+    isHeaderSeparator?: boolean
+  } = {}
 ): string => {
   const gutters = forceGutters ? true : config.wrapWithGutters
+  let padding = " "
+
+  if (isHeaderSeparator && !config.padHeaderSeparator) {
+    padding = ""
+  }
 
   return (
-    (gutters ? "| " : "  ") +
-    columns.join(gutters ? " | " : "   ") +
-    (gutters ? " |" : "  ") +
+    (gutters ? `|${padding}` : ` ${padding}`) +
+    columns.join(gutters ? `${padding}|${padding}` : `${padding} ${padding}`) +
+    (gutters ? `${padding}|` : `${padding} `) +
     config.lineEnding
   )
 }
@@ -78,11 +89,11 @@ export const row = (
   }
 
   if (height === 1) {
-    return line(first, config, true)
+    return line(first, config, { forceGutters: true })
   }
 
   const lines = new Array(height)
-  lines[0] = line(first, config, true)
+  lines[0] = line(first, config, { forceGutters: true })
 
   for (let v = 1; v < height; v++) {
     lines[v] = new Array(width)
@@ -117,7 +128,8 @@ export const normalizeOptions = (
     columns: [],
     lineEnding: "\n",
     wrapWidth: Infinity,
-    wrapWithGutters: false
+    wrapWithGutters: false,
+    padHeaderSeparator: true
   }
 
   Object.assign(defaults, options)

tests/cases.ts

@@ -51,6 +51,14 @@ test("gutters", t => {
   t.is(result, cases.gutters.expected)
 })
 
+test("can disable header separator row padding", t => {
+  const result = tablemark(
+    cases.padHeaderSeparator.input,
+    cases.padHeaderSeparator.options
+  )
+  t.is(result, cases.padHeaderSeparator.expected)
+})
+
 test("pipes in content", t => {
   const result = tablemark(cases.pipes.input, cases.pipes.options)
   t.is(result, cases.pipes.expected)

tests/fixtures/inputs.ts

@@ -192,6 +192,25 @@ const testCases: Record<string, TestCase> = {
         "| Lee   | 23    | true  |"
       ].join(EOL) + EOL
   },
+  padHeaderSeparator: {
+    input: [
+      { name: "Bob", age: 21, isCool: false },
+      { name: "Sarah", age: 22, isCool: true },
+      { name: "Lee", age: 23, isCool: true }
+    ],
+    options: {
+      columns: [{ align: "left" }, { align: "right" }, { align: "center" }],
+      padHeaderSeparator: false
+    },
+    expected:
+      [
+        "| Name  |   Age | Is cool |",
+        "|:------|------:|:-------:|",
+        "| Bob   |    21 |  false  |",
+        "| Sarah |    22 |  true   |",
+        "| Lee   |    23 |  true   |"
+      ].join(EOL) + EOL
+  },
   pipes: {
     input: [{ content: "yes | no" }],
     expected: