branch: externals/parser-generator
commit 1d1e4e4bf8c0587112b524575aabdd6bfba07ccd
Author: Christian Johansson <christ...@cvj.se>
Commit: Christian Johansson <christ...@cvj.se>
More work on LL(k) parser
---
parser-generator-ll.el | 84 ++++++++++++++++++++++++++++++++++++++++++++++++--
parser-generator.el | 2 +-
2 files changed, 83 insertions(+), 3 deletions(-)
diff --git a/parser-generator-ll.el b/parser-generator-ll.el
index b120cce04a..2b2a22ff7d 100644
--- a/parser-generator-ll.el
+++ b/parser-generator-ll.el
@@ -50,14 +50,94 @@
(distinct-table-p (make-hash-table :test 'equal))
;; (1) Construct T_0, the LL(k) table associated with S {e}
(stack `((,(parser-generator--get-grammar-start) nil)))
- (stack-item))
+ (stack-item)
+ (k (max 1 parser-generator--look-ahead-number)))
(while stack
(setq stack-item (pop stack))
(let* ((production (nth 0 stack-item))
(dot-look-ahead (nth 1 stack-item))
(first-production (parser-generator--first production nil t t))
(first-dot-look-ahead (parser-generator--first dot-look-ahead nil
t t))
- (look-aheads (parser-generator--merge-max-terminals
first-production first-dot-look-ahead)))
+ (look-aheads))
+ (cond
+ ((and first-production
+ (not first-dot-look-ahead))
+ (setq
+ look-aheads
+ (parser-generator--merge-max-terminals
+ first-production
+ nil
+ k)))
+ ((and first-dot-look-ahead
+ (not first-production))
+ (setq
+ look-aheads
+ (parser-generator--merge-max-terminals
+ nil
+ first-dot-look-ahead
+ k)))
+ ((and first-production
+ first-dot-look-ahead)
+ ;; Generate a new list of all permutations
+ ;; of first-production
+ ;; and first-dot-look-ahead
+ ;; with maximum length k
+ (let ((first-production-length
+ (length first-production))
+ (first-production-index 0)
+ (first-dot-look-ahead-length
+ (length first-dot-look-ahead))
+ (merged-look-aheds))
+ (while
+ (<
+ first-production-index
+ first-production-length)
+ (let ((first-production-element
+ (nth
+ first-production-index
+ first-production))
+ (first-dot-look-ahead-index 0))
+ (while
+ (<
+ first-dot-look-ahead-index
+ first-dot-look-ahead-length)
+ (let ((first-dot-look-ahead-element
+ (nth
+ first-dot-look-ahead-index
+ first-dot-look-ahead)))
+ (let ((merged-first-element
+ (parser-generator--merge-max-terminals
+ first-production-element
+ first-dot-look-ahead-element)))
+ (if merged-look-aheads
+ (setq
+ merged-look-aheads
+ (append
+ merged-look-aheads
+ merged-first-element))
+ (setq
+ merged-look-aheads
+ merged-first-element))))
+ (setq
+ first-dot-look-ahead-index
+ (1+ first-dot-look-ahead-index)))
+ (setq
+ first-production-index
+ (1+ first-production-index))))
+ (setq
+ merged-look-aheads
+ (parser-generator--distinct
+ merged-look-aheads))
+ (setq
+ look-aheads
+ merged-look-aheads))
+
+
+ )
+ (t (error
+ "Unexpected empty FIRST for production: %S and dot-look-ahead: %S"
+ production
+ dot-look-ahead)))
(parser-generator--debug
(message "production: %S" production)
(message "dot-look-ahead: %S" dot-look-ahead)
diff --git a/parser-generator.el b/parser-generator.el
index 498c210810..9bd2035a62 100644
--- a/parser-generator.el
+++ b/parser-generator.el
@@ -45,7 +45,7 @@
(defvar
parser-generator--debug
- nil
+ t
"Whether to print debug messages or not.")
(defvar
