From 39c932d3539c8b9bac130e430c859c5e47f83ef0 Mon Sep 17 00:00:00 2001
From: Ian Bicking <ian@ianbicking.org>
Date: Fri, 31 May 2024 13:03:37 -0500
Subject: [PATCH 1/2] Apply the patches from #465 to fix indentation

See https://github.com/ohmjs/ohm/issues/465#issuecomment-1977985628

This changes memoization some so it can consume dedents
---
 packages/ohm-js/src/MatchState.js  | 24 ++++++++++++++++++++----
 packages/ohm-js/src/pexprs-eval.js |  6 +++---
 2 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/packages/ohm-js/src/MatchState.js b/packages/ohm-js/src/MatchState.js
index afc676b0..34212b09 100644
--- a/packages/ohm-js/src/MatchState.js
+++ b/packages/ohm-js/src/MatchState.js
@@ -1,3 +1,4 @@
+import { StringBuffer } from './common.js';
 import {InputStream} from './InputStream.js';
 import {MatchResult} from './MatchResult.js';
 import {PosInfo} from './PosInfo.js';
@@ -234,10 +235,25 @@ export class MatchState {
       const actuals = app ? app.args : [];
       expr = expr.substituteParams(actuals);
     }
-    return (
-      this.getMemoizedTraceEntry(pos, expr) ||
-      new Trace(this.input, pos, this.inputStream.pos, expr, succeeded, bindings, this.trace)
-    );
+    const memoTrace = this.getMemoizedTraceEntry(pos, expr)
+    let indentsLessThanPos = 0
+    let indentsLessThanInputPos = 0
+    if (!memoTrace) {
+      const input = new StringBuffer()
+      for (let i = 0; i < this.input.length; i++) {
+        if (this.inputStream._indentationAt(i) !== 0) {
+          for (let numPlaces = this.inputStream._indentationAt(i); numPlaces !== 0; numPlaces += (numPlaces < 0 ? 1 : -1)) {
+            input.append(numPlaces < 0 ? "\u21e6" : "\u21e8")
+            if (i < pos) indentsLessThanPos += 1;
+            if (i < this.inputStream.pos) indentsLessThanInputPos += 1;
+          }
+        }
+        input.append(this.inputStream.source[i])
+      }
+      return new Trace(input.contents(), pos + indentsLessThanPos, this.inputStream.pos + indentsLessThanInputPos, expr, succeeded, bindings, this.trace)
+    } else {
+      return memoTrace;
+    }
   }
 
   isTracing() {
diff --git a/packages/ohm-js/src/pexprs-eval.js b/packages/ohm-js/src/pexprs-eval.js
index 32f74727..dfe8dda8 100644
--- a/packages/ohm-js/src/pexprs-eval.js
+++ b/packages/ohm-js/src/pexprs-eval.js
@@ -232,7 +232,7 @@ pexprs.Apply.prototype.handleCycle = function(state) {
   const memoKey = this.toMemoKey();
   let memoRec = posInfo.memo[memoKey];
 
-  if (currentLeftRecursion && currentLeftRecursion.headApplication.toMemoKey() === memoKey) {
+  if (memoRec && currentLeftRecursion && currentLeftRecursion.headApplication.toMemoKey() === memoKey) {
     // We already know about this left recursion, but it's possible there are "involved
     // applications" that we don't already know about, so...
     memoRec.updateInvolvedApplicationMemoKeys();
@@ -275,7 +275,7 @@ pexprs.Apply.prototype.reallyEval = function(state) {
   let memoRec;
 
   if (state.doNotMemoize) {
-    state.doNotMemoize = false;
+    // state.doNotMemoize = false;
   } else if (isHeadOfLeftRecursion) {
     value = this.growSeedResult(body, state, origPos, currentLR, value);
     origPosInfo.endLeftRecursion();
@@ -307,7 +307,7 @@ pexprs.Apply.prototype.reallyEval = function(state) {
 
   // Record trace information in the memo table, so that it is available if the memoized result
   // is used later.
-  if (state.isTracing() && memoRec) {
+  if (state.isTracing() && memoRec && !state.doNotMemoize) {
     const entry = state.getTraceEntry(origPos, this, succeeded, succeeded ? [value] : []);
     if (isHeadOfLeftRecursion) {
       common.assert(entry.terminatingLREntry != null || !succeeded);

From 454746e09fbff9b240859b462a5a2fb04ef55878 Mon Sep 17 00:00:00 2001
From: Ian Bicking <ian@ianbicking.org>
Date: Mon, 3 Jun 2024 14:16:19 -0500
Subject: [PATCH 2/2] When parsing whitespace-sensitive grammar, do not treat
 an empty line as an indent or dedent

This is a case like:

if foo:
  bar()

  baz()
---
 packages/ohm-js/src/findIndentation.js | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/packages/ohm-js/src/findIndentation.js b/packages/ohm-js/src/findIndentation.js
index 32a7befb..668827ea 100644
--- a/packages/ohm-js/src/findIndentation.js
+++ b/packages/ohm-js/src/findIndentation.js
@@ -19,7 +19,9 @@ export function findIndentation(input) {
 
     const indentPos = pos + indentSize;
 
-    if (indentSize > prevSize) {
+    if (!line.trim()) {
+      // Empty line, cannot be an indent or dedent.
+    } else if (indentSize > prevSize) {
       // Indent -- always only 1.
       stack.push(indentSize);
       result[indentPos] = 1;