From 8e400af0c03cf5011edd5124b23751ca32230260 Mon Sep 17 00:00:00 2001
From: Abbe Keultjes <flauwekeul@gmail.com>
Date: Fri, 22 Jul 2022 22:00:33 +0200
Subject: [PATCH] feat(grid/traversers): add repeatWith traverser

It's very similar to branch() but has the option to omit the hexes from the source traverser. Also,
the name is a little better (hopefully)
---
 src/grid/functions/index.ts      |  1 +
 src/grid/functions/repeatWith.ts | 25 +++++++++++++++++++++++++
 src/grid/traversers/rays.ts      |  3 ++-
 src/grid/traversers/rectangle.ts |  4 ++--
 src/grid/traversers/spiral.ts    |  4 ++--
 5 files changed, 32 insertions(+), 5 deletions(-)
 create mode 100644 src/grid/functions/repeatWith.ts

diff --git a/src/grid/functions/index.ts b/src/grid/functions/index.ts
index 0492f780..619f862d 100644
--- a/src/grid/functions/index.ts
+++ b/src/grid/functions/index.ts
@@ -3,3 +3,4 @@ export * from './concat'
 export * from './distance'
 export * from './neighborOf'
 export * from './repeat'
+export * from './repeatWith'
diff --git a/src/grid/functions/repeatWith.ts b/src/grid/functions/repeatWith.ts
new file mode 100644
index 00000000..ac9ba65b
--- /dev/null
+++ b/src/grid/functions/repeatWith.ts
@@ -0,0 +1,25 @@
+import { Hex } from '../../hex'
+import { Traverser } from '../types'
+import { concat } from './concat'
+
+// todo: use in rays (if it still has right to exist)
+// todo: probably move repeatWith, repeat and concat to grid/traversers/
+export function repeatWith<T extends Hex>(
+  sources: Traverser<T> | Traverser<T>[],
+  targets: Traverser<T> | Traverser<T>[],
+  // todo: isn't there a more elegant way than a config?
+  { includeSource = true } = {},
+): Traverser<T, T[]> {
+  return function repeatWithTraverser(createHex, cursor) {
+    const hexes: T[] = []
+
+    for (const sourceCursor of concat(sources)(createHex, cursor)) {
+      if (includeSource) hexes.push(sourceCursor)
+      for (const hex of concat(targets)(createHex, sourceCursor)) {
+        hexes.push(hex)
+      }
+    }
+
+    return hexes
+  }
+}
diff --git a/src/grid/traversers/rays.ts b/src/grid/traversers/rays.ts
index 9895ffcc..fd1b930e 100644
--- a/src/grid/traversers/rays.ts
+++ b/src/grid/traversers/rays.ts
@@ -4,8 +4,9 @@ import { line } from './line'
 import { ring } from './ring'
 
 // todo:
+// - remove this file? If not: refactor to use repeatWith()?
 // - add option for arc in degrees?
-// - add to docs that duplicate hexes are returned (or make this configurable? Or add transformer that dedupes?)
+// - add to docs that duplicate hexes are returned (or make this configurable? Or add transducer that dedupes?)
 export function rays<T extends Hex>(options: RaysWithLengthOptions): Traverser<T, T[]>
 export function rays<T extends Hex>(options: RaysToHexOptions): Traverser<T, T[]>
 export function rays<T extends Hex>({
diff --git a/src/grid/traversers/rectangle.ts b/src/grid/traversers/rectangle.ts
index 36e13491..3d6737bb 100644
--- a/src/grid/traversers/rectangle.ts
+++ b/src/grid/traversers/rectangle.ts
@@ -1,7 +1,7 @@
 import { Compass, CompassDirection } from '../../compass'
 import { Hex, HexCoordinates, hexToOffset, OffsetCoordinates } from '../../hex'
 import { isOffset, isTuple, tupleToCube } from '../../utils'
-import { branch } from '../functions'
+import { repeatWith } from '../functions'
 import { Traverser } from '../types'
 import { line } from './line'
 
@@ -25,7 +25,7 @@ export function rectangle<T extends Hex>(
       ? optionsFromOpposingCorners(optionsOrCornerA as HexCoordinates, cornerB, createHex())
       : (optionsOrCornerA as RectangleOptions)
     const firstHex = createHex(start ?? cursor)
-    const hexes = branch<T>(
+    const hexes = repeatWith<T>(
       line({ start: firstHex, direction: Compass.rotate(direction, 2), length: height }),
       line({ direction, length: width - 1 }),
     )(createHex, firstHex)
diff --git a/src/grid/traversers/spiral.ts b/src/grid/traversers/spiral.ts
index e616bfd1..73cd0f89 100644
--- a/src/grid/traversers/spiral.ts
+++ b/src/grid/traversers/spiral.ts
@@ -1,6 +1,6 @@
 import { CompassDirection } from '../../compass'
 import { Hex, HexCoordinates } from '../../hex'
-import { branch } from '../functions'
+import { repeatWith } from '../functions'
 import { RotationLike, Traverser } from '../types'
 import { line } from './line'
 import { ring } from './ring'
@@ -8,7 +8,7 @@ import { ring } from './ring'
 export function spiral<T extends Hex>({ radius, start, rotation }: SpiralOptions): Traverser<T, T[]> {
   return function spiralTraverser(createHex, cursor) {
     const center = createHex(start ?? cursor)
-    return branch<T>(line({ start, direction: CompassDirection.N, length: radius }), ring({ center, rotation }))(
+    return repeatWith<T>(line({ start, direction: CompassDirection.N, length: radius }), ring({ center, rotation }))(
       createHex,
       cursor,
     )