branch: externals/parser-generator
commit d1f46827a56fa1307fd4b2c435efef0b6262b628
Author: Christian Johansson <christ...@cvj.se>
Commit: Christian Johansson <christ...@cvj.se>
Added a function that converts a FIRST-item to a look-ahead item
---
parser-generator-lr.el | 13 ++++++++++---
parser-generator.el | 14 ++++++++++++++
2 files changed, 24 insertions(+), 3 deletions(-)
diff --git a/parser-generator-lr.el b/parser-generator-lr.el
index 1def311..7cc030e 100644
--- a/parser-generator-lr.el
+++ b/parser-generator-lr.el
@@ -95,15 +95,22 @@
(while (and
searching-match
(< eff-index eff-length))
- (setq eff-item (nth eff-index eff))
- (if
(parser-generator--valid-look-ahead-p eff-item)
+ (setq
+ eff-item
+ (parser-generator--first-to-lookahead
+ (nth eff-index eff)))
+ (if
+ (parser-generator--valid-look-ahead-p
+ eff-item)
(let ((hash-key
(format "%s-%s-%s" goto-index
state eff-item)))
(unless (gethash hash-key
added-actions)
(puthash hash-key t
added-actions)
(setq searching-match nil)))
(parser-generator--debug
- (message "Not valid look-ahead: %s"
eff-item)))
+ (message
+ "Not valid look-ahead: %s"
+ eff-item)))
(setq eff-index (1+ eff-index)))
(unless searching-match
diff --git a/parser-generator.el b/parser-generator.el
index 296cc0a..9ab4716 100644
--- a/parser-generator.el
+++ b/parser-generator.el
@@ -827,6 +827,20 @@
(parser-generator--debug
(message "Generated F-sets"))))
+(defun parser-generator--first-to-lookahead (first)
+ "Replace all e-identifiers with eof-identifiers in FIRST."
+ (let ((look-ahead))
+ (dolist (symbol first)
+ (if (parser-generator--valid-e-p
+ symbol)
+ (push
+ parser-generator--eof-identifier
+ look-ahead)
+ (push
+ symbol
+ look-ahead)))
+ (nreverse look-ahead)))
+
(defun parser-generator--merge-max-terminals (a b k)
"Merge terminals from A and B to a maximum length of K."
(let ((merged)
