branch: externals/parser-generator
commit 21164b6781b6b58973d26e988e48bbf19c0cb2e5
Author: Christian Johansson <christ...@cvj.se>
Commit: Christian Johansson <christ...@cvj.se>
Added documentation for (lr-items)
---
README.md | 31 +++++++++++++++++++++++++++++++
1 file changed, 31 insertions(+)
diff --git a/README.md b/README.md
index 204af73..8d1196f 100644
--- a/README.md
+++ b/README.md
@@ -130,6 +130,7 @@ Calculate the e-free-first look-ahead number of terminals
of sentential-form `S`
Calculate the look-ahead number of terminals possibly following S.
``` emacs-lisp
+(require 'ert)
(parser--set-grammar '((S A B) (a c d f) ((S (A a)) (A B) (B (c f) d)) S))
(parser--set-look-ahead-number 2)
(should
@@ -138,6 +139,36 @@ Calculate the look-ahead number of terminals possibly
following S.
(parser--follow 'A)))
```
+### LR(k) items - V(S)
+
+Calculate the set of LR(k) items valid for any viable prefix S.
+
+``` emacs-lisp
+(require 'ert)
+(parser--set-grammar '((Sp S) (a b) ((Sp S) (S (S a S b)) (S e)) Sp))
+(parser--set-look-ahead-number 1)
+(should
+ (equal
+ '((S nil nil (a))
+ (S nil (S a S b) (a))
+ (S nil nil (e))
+ (S nil (S a S b) (e))
+ (Sp nil (S) (e)))
+ (parser--lr-items 'e)))
+```
+
+``` emacs-lisp
+(require 'ert)
+(parser--set-grammar '((Sp S) (a b) ((Sp S) (S (S a S b)) (S e)) Sp))
+(parser--set-look-ahead-number 1)
+(should
+ (equal
+ '((Sp (S) nil (e))
+ (S (S) (a S b) (e))
+ (S (S) (a S b) (a)))
+ (parser--lr-items 'S)))
+```
+
## Test
Run in terminal `make clean && make tests && make compile`
