branch: externals/parser-generator
commit e2f43472af09e427051d054e78bd3669866bdd2d
Author: Christian Johansson <christ...@cvj.se>
Commit: Christian Johansson <christ...@cvj.se>
More work on f-set generation with e-identifiers
---
parser-generator.el | 129 +++++++++++++++++++++++++++++++++++++++++-----------
1 file changed, 103 insertions(+), 26 deletions(-)
diff --git a/parser-generator.el b/parser-generator.el
index b3da68e..56e5a5b 100644
--- a/parser-generator.el
+++ b/parser-generator.el
@@ -10,10 +10,6 @@
;;; Variables:
-(defvar parser-generator--allow-e-productions
- nil
- "Flag whether e-productions is allowed or not.")
-
(defvar parser-generator--debug
nil
"Whether to print debug messages or not.")
@@ -311,10 +307,6 @@
(error "Invalid look-ahead number k!"))
(setq parser-generator--look-ahead-number k))
-(defun parser-generator--set-allow-e-productions (flag)
- "Set FLAG whether e-productions is allowed or not."
- (setq parser-generator--allow-e-productions flag))
-
(defun parser-generator-set-grammar (G)
"Set grammar G.."
(unless (parser-generator--valid-grammar-p G)
@@ -771,6 +763,7 @@
(let ((sub-terminal-set (car sub-terminal-sets)))
(unless (= (length sub-terminal-sets) 1)
+
;; Should branch off here, each unique
permutation should be included in set
;; Follow the first alternative in this
scope but follow the rest in separate scopes
(let ((sub-terminal-index 0))
@@ -786,11 +779,35 @@
(parser-generator--debug
(message "alternative-set is the
e identifier"))
- ;; TODO Branch off here in two
separate tracks
+ ;; Branch off here in two separate
tracks, one with the e-identifier appended and one without
+ (if disallow-e-first
+ (progn
+ (when (and
+
all-leading-terminals-p
+ (>
leading-terminals-count 0))
+ (parser-generator--debug
(message "branched off 2"))
+ ;; Branch off here with a
separate track where this e-identifier is ignored
+ (push `(
+ ,leading-terminals
+
,all-leading-terminals-p
+ ,(1+
input-tape-index))
+ stack))
+
+ (setq
alternative-all-leading-terminals-p nil))
+
+ ;; Add e-identifier to leading
terminals when
+ ;; we have not found any leading
terminals
+ ;; and we are at the last symbol
in input-tape
+
+ (when all-leading-terminals-p
+ (parser-generator--debug
(message "branched off 1"))
+ ;; Branch off here with a
separate track where this e-identifier is ignored
+ (push `(
+ ,leading-terminals
+
,all-leading-terminals-p
+ ,(1+ input-tape-index))
+ stack))
- (when (and
- disallow-e-first
- (= leading-terminals-count
0))
(setq
alternative-all-leading-terminals-p nil)))
(let ((sub-rhs-leading-terminals
@@ -807,6 +824,7 @@
(butlast
sub-rhs-leading-terminals
(- (length
sub-rhs-leading-terminals) k))))
+ (parser-generator--debug (message
"branched off 3"))
(push `(
,sub-rhs-leading-terminals
,alternative-all-leading-terminals-p
@@ -817,34 +835,94 @@
(parser-generator--debug
(message "Sub-terminal-set: %s"
sub-terminal-set))
- ;; TODO when sub-terminal-set is the
e-identifier branch off in two separate tracks
+ ;; When sub-set only contains the e identifier
+ (if (parser-generator--valid-e-p
+ (car sub-terminal-set))
+ (progn
+ (parser-generator--debug
+ (message "sub-terminal-set is the e
identifier"))
+
+ ;; Branch off here in two separate
tracks, one with the e-identifier appended and one without
+ (if disallow-e-first
+ (progn
+ (when (and
+ all-leading-terminals-p
+ (> leading-terminals-count
0))
+ ;; Branch off here with a
separate track where this e-identifier is ignored
+ (parser-generator--debug
(message "branched off 4"))
+ (push `(
+ ,leading-terminals
+ ,all-leading-terminals-p
+ ,(1+ input-tape-index))
+ stack))
+
+ (setq all-leading-terminals-p nil))
+
+ ;; Add e-identifier to leading
terminals when
+ ;; we have not found any leading
terminals
+ ;; and we are at the last symbol in
input-tape
+
+ (when all-leading-terminals-p
+ ;; Branch off here with a separate
track where this e-identifier is ignored
+ (parser-generator--debug (message
"branched off 5"))
+ (push `(
+ ,leading-terminals
+ ,all-leading-terminals-p
+ ,(1+ input-tape-index))
+ stack))
+
+ (setq leading-terminals (append
leading-terminals sub-terminal-set))
+ (setq leading-terminals-count (+
leading-terminals-count (length sub-terminal-set)))
+ (when (> leading-terminals-count k)
+ (setq leading-terminals (butlast
leading-terminals (- leading-terminals-count k)))
+ (setq leading-terminals-count k))
+ (setq all-leading-terminals-p nil)))
+
+ (setq leading-terminals (append
leading-terminals sub-terminal-set))
+ (setq leading-terminals-count (+
leading-terminals-count (length sub-terminal-set)))
+ (when (> leading-terminals-count k)
+ (setq leading-terminals (butlast
leading-terminals (- leading-terminals-count k)))
+ (setq leading-terminals-count k)))))
- (setq leading-terminals (append
leading-terminals sub-terminal-set))
- (setq leading-terminals-count (+
leading-terminals-count (length sub-terminal-set)))
- (when (> leading-terminals-count k)
- (setq leading-terminals (butlast
leading-terminals (- leading-terminals-count k)))
- (setq leading-terminals-count k))))
(parser-generator--debug
(message "Found no subsets for %s %s" rhs-element
(1- i)))
(setq expanded-all nil)
(setq all-leading-terminals-p nil)))
+
(setq expanded-all nil)
(setq all-leading-terminals-p nil)))
((equal rhs-type 'E-IDENTIFIER)
(if disallow-e-first
- (when (= leading-terminals-count 0)
+ (progn
+ (when (and
+ all-leading-terminals-p
+ (> leading-terminals-count 0))
+ ;; Branch off here with a separate track where this
e-identifier is ignored
+ (parser-generator--debug (message "branched off 6"))
+ (push `(
+ ,leading-terminals
+ ,all-leading-terminals-p
+ ,(1+ input-tape-index))
+ stack))
+
(setq all-leading-terminals-p nil))
;; Add e-identifier to leading terminals when
;; we have not found any leading terminals
;; and we are at the last symbol in input-tape
- ;; TODO Branch off here with two separate tracks
- (when (and
- (= leading-terminals-count 0)
- (= input-tape-index (1- input-tape-length)))
+ (when all-leading-terminals-p
+ ;; Branch off here with a separate track where this
e-identifier is ignored
+ (parser-generator--debug (message "branched off 7"))
+ (push `(
+ ,leading-terminals
+ ,all-leading-terminals-p
+ ,(1+ input-tape-index))
+ stack))
+
(setq leading-terminals (append leading-terminals
rhs-element))
- (setq leading-terminals-count (1+
leading-terminals-count)))))
+ (setq leading-terminals-count (1+
leading-terminals-count))
+ (setq all-leading-terminals-p nil)))
((equal rhs-type 'TERMINAL)
(setq leading-terminals (append leading-terminals (list
rhs-element)))
@@ -863,8 +941,7 @@
(setq β (list β)))
(unless (parser-generator--valid-sentential-form-p β)
(error "Invalid sentential form β! %s" β))
- (let ((productions (parser-generator--get-grammar-productions))
- (k parser-generator--look-ahead-number))
+ (let ((k parser-generator--look-ahead-number))
;; Generate F-sets only once per grammar
(parser-generator--generate-f-sets)
