feat: debug conflict resolution graph printing (#150) by halotukozak · Pull Request #301 · halotukozak/alpaca

halotukozak · 2026-03-04T14:49:39Z

Summary

Implement debug conflict resolution graph printing to file (Issue Debug conflict resolution graph #150)

🤖 Generated with Claude Code

…ue 150)

github-actions · 2026-03-04T14:53:00Z

🏃 Runtime Benchmark

Benchmark	Base (master)	Current (issue-150-mermaid-debug)	Diff

Copilot

Pull request overview

Adds Mermaid graph output for the conflict resolution precedence graph to help debug/visualize conflict resolution rules (Issue #150).

Changes:

Emit a new conflictResolutions.mmd debug file during table creation.
Add ConflictResolutionTable.toMermaid to render the precedence graph in Mermaid format.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
`src/alpaca/internal/parser/createTables.scala`	Writes Mermaid debug output alongside the existing conflict resolution debug table output.
`src/alpaca/internal/parser/ConflictResolution.scala`	Implements Mermaid rendering for the conflict resolution graph.

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Copilot · 2026-03-04T14:54:53Z

src/alpaca/internal/parser/ConflictResolution.scala

+    def toMermaid(using Log): String =
+      val sb = new StringBuilder
+      sb.append("graph TD\n")


toMermaid is new behavior and is now used to emit a debug artifact from createTablesImpl, but there’s no unit test coverage to ensure the output remains valid Mermaid (especially for token/production names with special characters) and stable over time. Adding a focused test in test/src/alpaca/internal/parser that builds a small ConflictResolutionTable and asserts key nodes/edges/escaping would help prevent regressions.

Copilot · 2026-03-04T14:54:54Z

src/alpaca/internal/parser/ConflictResolution.scala

+      def nodeName(key: ConflictKey): String =
+        val raw = key match
+          case p: Production => p.name match
+            case null => show"$p"
+            case name: String => name
+          case s: String => show"Token($s)"
+        // Escape special chars for mermaid
+        raw.replace(" ", "_").replace("(", "[").replace(")", "]").replace("->", "_to_").replace("ε", "epsilon")
+
+      def nodeLabel(key: ConflictKey): String = key match
+        case p: Production => show"$p"
+        case s: String => show"Token($s)"
+
+      val nodes = (table.keySet ++ table.values.flatten).toSet
+      for node <- nodes do
+        sb.append(s"  ${nodeName(node)}[\"${nodeLabel(node)}\"]\n")
+
+      for (from, toSet) <- table; to <- toSet do
+        sb.append(s"  ${nodeName(from)} --> ${nodeName(to)}\n")


nodeName is used as the Mermaid node identifier, but the current “escaping” can still produce invalid IDs and collisions (e.g., replacing ( with [/] introduces Mermaid syntax chars; token/production names can contain many other non-identifier characters; production names can collide with token-derived names). Consider generating a safe, unique ID per ConflictKey (e.g., P_/T_ prefix + stable hash or an indexed map) and keep the human-readable text only in the label.

Suggested change

def nodeName(key: ConflictKey): String =

val raw = key match

case p: Production => p.name match

case null => show"$p"

case name: String => name

case s: String => show"Token($s)"

// Escape special chars for mermaid

raw.replace(" ", "_").replace("(", "[").replace(")", "]").replace("->", "_to_").replace("ε", "epsilon")

def nodeLabel(key: ConflictKey): String = key match

case p: Production => show"$p"

case s: String => show"Token($s)"

val nodes = (table.keySet ++ table.values.flatten).toSet

for node <- nodes do

sb.append(s" ${nodeName(node)}[\"${nodeLabel(node)}\"]\n")

for (from, toSet) <- table; to <- toSet do

sb.append(s" ${nodeName(from)} --> ${nodeName(to)}\n")

// Generate safe, unique Mermaid node identifiers per ConflictKey.

val idMap = mutable.LinkedHashMap.empty[ConflictKey, String]

var prodIdx = 0

var tokIdx = 0

var otherIdx = 0

def nodeId(key: ConflictKey): String =

idMap.getOrElseUpdate(

key,

key match

case _: Production =>

prodIdx += 1

s"P_$prodIdx"

case _: String =>

tokIdx += 1

s"T_$tokIdx"

case _ =>

otherIdx += 1

s"N_$otherIdx"

)

def nodeLabel(key: ConflictKey): String = key match

case p: Production => show"$p"

case s: String => show"Token($s)"

val nodes = (table.keySet ++ table.values.flatten).toSet

for node <- nodes do

sb.append(s" ${nodeId(node)}[\"${nodeLabel(node)}\"]\n")

for (from, toSet) <- table; to <- toSet do

sb.append(s" ${nodeId(from)} --> ${nodeId(to)}\n")

Copilot · 2026-03-04T14:54:54Z

src/alpaca/internal/parser/ConflictResolution.scala

+      val nodes = (table.keySet ++ table.values.flatten).toSet
+      for node <- nodes do
+        sb.append(s"  ${nodeName(node)}[\"${nodeLabel(node)}\"]\n")


nodeLabel is injected into [...] with double quotes, but the label text isn’t escaped. Since token names (and production names) can include characters like ", ], or newlines, this can generate invalid Mermaid. Escape label content (at least \, ", and newlines) before writing it, or use a safer encoding for labels.

Suggested change

val nodes = (table.keySet ++ table.values.flatten).toSet

for node <- nodes do

sb.append(s" ${nodeName(node)}[\"${nodeLabel(node)}\"]\n")

def escapeLabel(label: String): String =

label

.replace("\\", "\\\\")

.replace("\"", "\\\"")

.replace("\n", "\\n")

.replace("\r", "\\r")

val nodes = (table.keySet ++ table.values.flatten).toSet

for node <- nodes do

sb.append(s" ${nodeName(node)}[\"${escapeLabel(nodeLabel(node))}\"]\n")

Copilot · 2026-03-04T14:54:55Z

src/alpaca/internal/parser/ConflictResolution.scala

+      for node <- nodes do
+        sb.append(s"  ${nodeName(node)}[\"${nodeLabel(node)}\"]\n")
+
+      for (from, toSet) <- table; to <- toSet do


The Mermaid output iteration order is not deterministic (nodes is a Set and table is a Map), so the .mmd file may change between runs even when the underlying graph is the same. For debug artifacts that are intended to be diffed, consider sorting nodes/edges (e.g., by stable ID or label) before appending to the StringBuilder.

Suggested change

for node <- nodes do

sb.append(s" ${nodeName(node)}[\"${nodeLabel(node)}\"]\n")

for (from, toSet) <- table; to <- toSet do

// Sort nodes to ensure deterministic Mermaid output

for node <- nodes.toList.sortBy(nodeName) do

sb.append(s" ${nodeName(node)}[\"${nodeLabel(node)}\"]\n")

// Sort edges (both sources and targets) for deterministic ordering

for

(from, toSet) <- table.toList.sortBy { case (fromKey, _) => nodeName(fromKey) }

to <- toSet.toList.sortBy(nodeName)

do

codecov · 2026-03-04T14:55:15Z

Codecov Report

❌ Patch coverage is 0% with 18 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...rc/alpaca/internal/parser/ConflictResolution.scala	0.00%	18 Missing ⚠️

@@            Coverage Diff            @@
##             master     #301   +/-   ##
=========================================
  Coverage          ?   40.35%           
=========================================
  Files             ?       35           
  Lines             ?      451           
  Branches          ?        0           
=========================================
  Hits              ?      182           
  Misses            ?      269           
  Partials          ?        0

Files with missing lines	Coverage Δ
...rc/alpaca/internal/parser/ConflictResolution.scala	`0.00% <0.00%> (ø)`

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github-actions · 2026-03-04T15:03:16Z

📊 Test Compilation Benchmark

Branch	Average Time
Base (master)	52.061s
Current (issue-150-mermaid-debug)	51.158s

Result: Current branch is 0.903s faster (1.73%) ✅

feat: implement debug conflict resolution graph printing to file (Iss…

4e072dd

…ue 150)

Copilot AI review requested due to automatic review settings March 4, 2026 14:49

github-actions bot added enhancement New feature or request Parser labels Mar 4, 2026

Copilot started reviewing on behalf of halotukozak March 4, 2026 14:50 View session

Copilot AI reviewed Mar 4, 2026

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halotukozak mentioned this pull request Mar 4, 2026

Debug conflict resolution graph #150

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feat: debug conflict resolution graph printing (#150)#301

feat: debug conflict resolution graph printing (#150)#301
halotukozak wants to merge 1 commit intomasterfrom
issue-150-mermaid-debug

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-      val nodes = (table.keySet ++ table.values.flatten).toSet
-      for node <- nodes do
-        sb.append(s"  ${nodeName(node)}[\"${nodeLabel(node)}\"]\n")
+      def escapeLabel(label: String): String =
+        label
+          .replace("\\", "\\\\")
+          .replace("\"", "\\\"")
+          .replace("\n", "\\n")
+          .replace("\r", "\\r")
+      val nodes = (table.keySet ++ table.values.flatten).toSet
+      for node <- nodes do
+        sb.append(s"  ${nodeName(node)}[\"${escapeLabel(nodeLabel(node))}\"]\n")

-      for node <- nodes do
-        sb.append(s"  ${nodeName(node)}[\"${nodeLabel(node)}\"]\n")
-      for (from, toSet) <- table; to <- toSet do
+      // Sort nodes to ensure deterministic Mermaid output
+      for node <- nodes.toList.sortBy(nodeName) do
+        sb.append(s"  ${nodeName(node)}[\"${nodeLabel(node)}\"]\n")
+      // Sort edges (both sources and targets) for deterministic ordering
+      for
+        (from, toSet) <- table.toList.sortBy { case (fromKey, _) => nodeName(fromKey) }
+        to <- toSet.toList.sortBy(nodeName)
+      do

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