From 88cce7361c69636161470a84dbfb42fb723f4c07 Mon Sep 17 00:00:00 2001
From: NeilBrown <neilb@suse.de>
Date: Thu, 2 Oct 2014 20:58:38 +1000
Subject: [PATCH] parsergen: add since_indent to stack frame.

This counts frames since last indent.
It is used to determine when an OUT can be canceled and when we must
force a reduction.

Signed-off-by: NeilBrown <neil@brown.name>
---
 csrc/parsergen.mdc | 47 ++++++++++++++++++++++++++++++++++------------
 1 file changed, 35 insertions(+), 12 deletions(-)

diff --git a/csrc/parsergen.mdc b/csrc/parsergen.mdc
index 45fb09e..082cf11 100644
--- a/csrc/parsergen.mdc
+++ b/csrc/parsergen.mdc
@@ -2465,6 +2465,7 @@ before the beginning.
 			short starts_indented;
 			short indents;
 			short since_newline;
+			short since_indent;
 		} *stack;
 		void **asn_stack;
 		int stack_size;
@@ -2539,6 +2540,13 @@ So we walk down:
 			else
 				next->since_newline = 1;
 		}
+		if (next->indents)
+			next->since_indent = 0;
+		else if (p->tos)
+			next->since_indent = p->stack[p->tos-1].since_indent + 1;
+		else
+			next->since_indent = 1;
+
 		p->stack[p->tos] = *next;
 		p->asn_stack[p->tos] = asn;
 		p->tos++;
@@ -2664,18 +2672,32 @@ since the last state which could have been at the start of a line.
 				continue;
 			}
 			if (next.sym == TK_out) {
-				if (tos->indents > tos->starts_indented ||
-				    (tos->indents == 1 &&
-				     states[tos->state].reduce_size != 1)) {
-					tos->indents -= 1;
-					if (tos->indents <= tos->starts_indented) {
-						// no internal indent any more, reassess 'newline_permitted'
-						if (states[tos->state].starts_line)
-							tos->newline_permitted = 1;
-						else if (p.tos > 1)
-							tos->newline_permitted = p.stack[p.tos-2].newline_permitted;
-						else
-							tos->newline_permitted = 0;
+				if (states[tos->state].reduce_size >= 0 &&
+				    states[tos->state].reduce_size <= tos->since_indent)
+					goto force_reduce;
+				if (states[tos->state].min_prefix >= tos->since_indent) {
+					// OK to cancel
+					struct frame *in = tos - tos->since_indent;
+					in->indents -= 1;
+					if (in->indents == 0) {
+						/* Reassess since_indent and newline_permitted */
+						if (in > p.stack) {
+							in->since_indent = in[-1].since_indent + 1;
+							in->newline_permitted = in[-1].newline_permitted;
+						} else {
+							in->since_indent = 0;
+							in->newline_permitted = 0;
+						}
+						if (states[in->state].starts_line)
+							in->newline_permitted = 0;
+						while (in < tos) {
+							in += 1;
+							in->since_indent = in[-1].since_indent + 1;
+							if (states[in->state].starts_line)
+								in->newline_permitted = 1;
+							else
+								in->newline_permitted = in[-1].newline_permitted;
+						}
 					}
 					free(tk);
 					tk = NULL;
@@ -2782,6 +2804,7 @@ since the last state which could have been at the start of a line.
 					if (next.indents == 0)
 						break;
 					next.indents -= 1;
+					// FIXME update since_indent here
 				}
 			}
 			if (p.tos == 0 && tk->num == TK_eof)
-- 
2.43.0