From 9813dd19d2c8c41e85382a459973561501f707d4 Mon Sep 17 00:00:00 2001
From: ShikiSuen <shikisuen@outlook.com>
Date: Thu, 12 May 2022 22:25:18 +0800
Subject: [PATCH] Megrez::Builder // Allow defining max span length on init.

- Also use for loop in lieu of while loop in Megrez.
---
 .../Megrez/1_BlockReadingBuilder.swift        | 27 +++++++++----------
 .../LanguageParsers/Megrez/1_Walker.swift     | 15 ++++++-----
 .../LanguageParsers/Megrez/2_Grid.swift       | 25 +++++------------
 3 files changed, 27 insertions(+), 40 deletions(-)

diff --git a/Source/Modules/LanguageParsers/Megrez/1_BlockReadingBuilder.swift b/Source/Modules/LanguageParsers/Megrez/1_BlockReadingBuilder.swift
index 652ddc4c..d07d3af9 100644
--- a/Source/Modules/LanguageParsers/Megrez/1_BlockReadingBuilder.swift
+++ b/Source/Modules/LanguageParsers/Megrez/1_BlockReadingBuilder.swift
@@ -25,15 +25,16 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 extension Megrez {
   public class BlockReadingBuilder {
-    let kMaximumBuildSpanLength = 10  // 規定最多可以組成的詞的字數上限為 10
+    var mutMaximumBuildSpanLength = 10
     var mutCursorIndex: Int = 0
     var mutReadings: [String] = []
     var mutGrid: Grid = .init()
     var mutLM: LanguageModel
     var mutJoinSeparator: String = ""
 
-    public init(lm: LanguageModel) {
+    public init(lm: LanguageModel, length: Int = 10) {
       mutLM = lm
+      mutMaximumBuildSpanLength = length
     }
 
     public func clear() {
@@ -87,15 +88,13 @@ extension Megrez {
         return false
       }
 
-      var i = 0
-      while i < count {
-        if mutCursorIndex != 0 {
+      for _ in 0..<count {
+        if mutCursorIndex > 0 {
           mutCursorIndex -= 1
         }
         mutReadings.removeFirst()
         mutGrid.shrinkGridByOneAt(location: 0)
         build()
-        i += 1
       }
 
       return true
@@ -113,15 +112,17 @@ extension Megrez {
       // if (mutLM == nil) { return } // 這個出不了 nil，所以註釋掉。
 
       let itrBegin: Int =
-        (mutCursorIndex < kMaximumBuildSpanLength) ? 0 : mutCursorIndex - kMaximumBuildSpanLength
-      let itrEnd: Int = min(mutCursorIndex + kMaximumBuildSpanLength, mutReadings.count)
+        (mutCursorIndex < mutMaximumBuildSpanLength) ? 0 : mutCursorIndex - mutMaximumBuildSpanLength
+      let itrEnd: Int = min(mutCursorIndex + mutMaximumBuildSpanLength, mutReadings.count)
 
-      var p = itrBegin
-      while p < itrEnd {
-        var q = 1
-        while q <= kMaximumBuildSpanLength, p + q <= itrEnd {
+      for p in itrBegin..<itrEnd {
+        for q in 1..<mutMaximumBuildSpanLength {
+          if p + q > itrEnd {
+            break
+          }
           let strSlice = mutReadings[p..<(p + q)]
           let combinedReading: String = join(slice: strSlice, separator: mutJoinSeparator)
+
           if !mutGrid.hasMatchedNode(location: p, spanningLength: q, key: combinedReading) {
             let unigrams: [Unigram] = mutLM.unigramsFor(key: combinedReading)
             if !unigrams.isEmpty {
@@ -129,9 +130,7 @@ extension Megrez {
               mutGrid.insertNode(node: n, location: p, spanningLength: q)
             }
           }
-          q += 1
         }
-        p += 1
       }
     }
 
diff --git a/Source/Modules/LanguageParsers/Megrez/1_Walker.swift b/Source/Modules/LanguageParsers/Megrez/1_Walker.swift
index bf98aaea..d0f68b3a 100644
--- a/Source/Modules/LanguageParsers/Megrez/1_Walker.swift
+++ b/Source/Modules/LanguageParsers/Megrez/1_Walker.swift
@@ -50,20 +50,20 @@ extension Megrez {
         }
       }
 
-      // 只檢查前 X 個 NodeAnchor 是否有 node。
-      // 這裡有 abs 是為了防止有白癡填負數。
-      var border: Int = nodes.count
-      if nodesLimit > 0 {
-        border = min(nodes.count, abs(nodesLimit))
-      }
+      for (i, n) in nodes.enumerated() {
+        // 只檢查前 X 個 NodeAnchor 是否有 node。
+        // 這裡有 abs 是為了防止有白癡填負數。
+        if abs(nodesLimit) > 0, i == abs(nodesLimit) - 1 {
+          break
+        }
 
-      for n in nodes[0..<border] {
         var n = n
         guard let nNode = n.node else {
           continue
         }
 
         n.accumulatedScore = accumulatedScore + nNode.score()
+
         // 利用 Spanning Length 來決定權重。
         // 這樣一來，例：「再見」比「在」與「見」的權重更高。
         if balanced {
@@ -75,6 +75,7 @@ extension Megrez {
           at: location - n.spanningLength,
           score: n.accumulatedScore
         )
+
         path.insert(n, at: 0)
 
         paths.append(path)
diff --git a/Source/Modules/LanguageParsers/Megrez/2_Grid.swift b/Source/Modules/LanguageParsers/Megrez/2_Grid.swift
index 355c6bf8..961a03a3 100644
--- a/Source/Modules/LanguageParsers/Megrez/2_Grid.swift
+++ b/Source/Modules/LanguageParsers/Megrez/2_Grid.swift
@@ -38,10 +38,8 @@ extension Megrez {
     public func insertNode(node: Node, location: Int, spanningLength: Int) {
       if location >= mutSpans.count {
         let diff = location - mutSpans.count + 1
-        var i = 0
-        while i < diff {
+        for _ in 0..<diff {
           mutSpans.append(Span())
-          i += 1
         }
       }
       mutSpans[location].insert(node: node, length: spanningLength)
@@ -59,11 +57,9 @@ extension Megrez {
     public func expandGridByOneAt(location: Int) {
       mutSpans.append(Span())
       if location > 0, location < mutSpans.count {
-        var i = 0
-        while i < location {
+        for i in 0..<location {
           // zaps overlapping spans
           mutSpans[i].removeNodeOfLengthGreaterThan(location - i)
-          i += 1
         }
       }
     }
@@ -74,11 +70,9 @@ extension Megrez {
       }
 
       mutSpans.remove(at: location)
-      var i = 0
-      while i < location {
+      for i in 0..<location {
         // zaps overlapping spans
         mutSpans[i].removeNodeOfLengthGreaterThan(location - i)
-        i += 1
       }
     }
 
@@ -87,8 +81,7 @@ extension Megrez {
     public func nodesEndingAt(location: Int) -> [NodeAnchor] {
       var results: [NodeAnchor] = []
       if !mutSpans.isEmpty, location <= mutSpans.count {
-        var i = 0
-        while i < location {
+        for i in 0..<location {
           let span = mutSpans[i]
           if i + span.maximumLength >= location {
             if let np = span.node(length: location - i) {
@@ -101,7 +94,6 @@ extension Megrez {
               )
             }
           }
-          i += 1
         }
       }
       return results
@@ -110,14 +102,11 @@ extension Megrez {
     public func nodesCrossingOrEndingAt(location: Int) -> [NodeAnchor] {
       var results: [NodeAnchor] = []
       if !mutSpans.isEmpty, location <= mutSpans.count {
-        var i = 0
-        while i < location {
+        for i in 0..<location {
           let span = mutSpans[i]
           if i + span.maximumLength >= location {
-            var j = 1
-            while j <= span.maximumLength {
+            for j in 1...span.maximumLength {
               if i + j < location {
-                j += 1
                 continue
               }
               if let np = span.node(length: j) {
@@ -129,10 +118,8 @@ extension Megrez {
                   )
                 )
               }
-              j += 1
             }
           }
-          i += 1
         }
       }
       return results