branch: externals/parser-generator
commit e4658d9d2b2c07c68cae2c9f90c5890d69338c70
Author: Christian Johansson <christ...@cvj.se>
Commit: Christian Johansson <christ...@cvj.se>
LR action-table generation is now using context-sensitive precedence
resolution for reduce/reduce conflicts
---
parser-generator-lr.el | 138 ++++++++++++++++++-------------------------------
1 file changed, 49 insertions(+), 89 deletions(-)
diff --git a/parser-generator-lr.el b/parser-generator-lr.el
index d899425..4f132bd 100644
--- a/parser-generator-lr.el
+++ b/parser-generator-lr.el
@@ -390,6 +390,7 @@
goto-index
u)))
+ ;; Check if we have an action on this
symbol already
(when
(gethash
index-hash-key
@@ -402,9 +403,9 @@
index-hash-key
index-symbols)))
(if
-
(parser-generator-lr--symbol-takes-precedence-p
- (car a)
- (car b))
+
(parser-generator-lr--production-takes-precedence-p
+ (car (cdr a))
+ (car (cdr b)))
(progn
(parser-generator--debug
(message
@@ -992,8 +993,7 @@
b-production-number)
(progn
(unless
-
(parser-generator-lr--conflict-can-be-resolved-by-attributes
- a-follow-full
+
(parser-generator-lr--conflict-can-be-resolved-by-context
a-production-number
b-production-number)
(when
@@ -1025,90 +1025,50 @@
(setq set-index (1+ set-index)))
valid-p))
-;; TODO Need to consider production-numbers as well
-(defun parser-generator-lr--symbol-takes-precedence-p (a b &optional
a-production-number b-production-number)
- "Return t if A takes precedence over B, otherwise nil. Optionally check for
predence rules related to A-PRODUCTION-NUMBER and B-PRODUCTION-NUMBER."
- (let ((takes-precedence)
- (a-global-reference)
- (a-precedence)
- (b-global-reference)
- (b-precedence))
- (unless
- parser-generator-lr--precedence-comparison-function
- (error
- "Missing function to compare precedence!"))
- (when
- (listp a)
- (setq
- a-global-reference
- (plist-get
- (car (cdr a))
- parser-generator-lr--context-sensitive-precedence-attribute)))
- (when
- (listp b)
- (setq
- b-global-reference
- (plist-get
- (car (cdr b))
- parser-generator-lr--context-sensitive-precedence-attribute)))
- (if
- (listp a)
- (setq
- a-precedence
- (gethash
- (car a)
- parser-generator-lr--global-precedence-table))
- (setq
- a-precedence
- (gethash
- a
- parser-generator-lr--global-precedence-table)))
- (if
- (listp b)
- (setq
- b-precedence
- (gethash
- (car b)
- parser-generator-lr--global-precedence-table))
- (setq
- b-precedence
- (gethash
- b
- parser-generator-lr--global-precedence-table)))
- (when
- a-global-reference
- (setq
- a-precedence
- (gethash
- a-global-reference
- parser-generator-lr--global-precedence-table)))
- (when
- b-global-reference
- (setq
- b-precedence
- (gethash
- b-global-reference
- parser-generator-lr--global-precedence-table)))
- (condition-case
- errors
- (let ((comparison
- (funcall
- parser-generator-lr--precedence-comparison-function
- a-precedence
- b-precedence)))
- (setq
- takes-precedence
- comparison))
- (error
- (error
- "Trying to compare '%S' with '%S' resulted in error: '%S'!"
- a-precedence
- b-precedence
- errors)))
- takes-precedence))
-
-(defun parser-generator-lr--conflict-can-be-resolved-by-attributes (symbol
&optional a-production-number b-production-number)
- "Return whether a conflict at SYMBOL can be resolved by context-sensitive
precedence-attributes. Optionally with A-PRODUCTION-NUMBER and
B-PRODUCTION-NUMBER."
+(defun parser-generator-lr--production-takes-precedence-p (a-production-number
b-production-number)
+ "Return t if A-PRODUCTION-NUMBER takes precedence over B-PRODUCTION-NUMBER,
otherwise nil."
+ (let ((a-precedence-value)
+ (b-precedence-value))
+
+ (let ((a-attributes
+ (gethash
+ a-production-number
+ parser-generator--table-productions-attributes)))
+ (when a-attributes
+ (let ((a-precedence-symbol
+ (plist-get
+ a-attributes
+ parser-generator-lr--context-sensitive-precedence-attribute)))
+ (when a-precedence-symbol
+ (setq
+ a-precedence-value
+ (gethash
+ a-precedence-symbol
+ parser-generator-lr--global-precedence-table))))))
+
+ (let ((b-attributes
+ (gethash
+ b-production-number
+ parser-generator--table-productions-attributes)))
+ (when b-attributes
+ (let ((b-precedence-symbol
+ (plist-get
+ b-attributes
+ parser-generator-lr--context-sensitive-precedence-attribute)))
+ (when b-precedence-symbol
+ (setq
+ b-precedence-value
+ (gethash
+ b-precedence-symbol
+ parser-generator-lr--global-precedence-table))))))
+
+ (funcall
+ parser-generator-lr--precedence-comparison-function
+ a-precedence-value
+ b-precedence-value)))
+
+(defun parser-generator-lr--conflict-can-be-resolved-by-context
(a-production-number b-production-number)
+ "Return whether a conflict can be solved by context between
A-PRODUCTION-NUMBER and B-PRODUCTION-NUMBER."
(let ((can-be-resolved)
(a-precedence-value)
(b-precedence-value))
