branch: externals/parser-generator
commit c992a542639a50d2f34b625afe5a0f97ff6ff327
Author: Christian Johansson <christ...@cvj.se>
Commit: Christian Johansson <christ...@cvj.se>
Added info in README.md about LR-items
---
README.md | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/README.md b/README.md
index aa3667c..66e088d 100644
--- a/README.md
+++ b/README.md
@@ -25,6 +25,23 @@ We use push down transducer (PDT) based algorithms:
#### Deterministic Shift-Reduce Parsing
#### LR(k)
#### Deterministic Right Parser for LR(k) Grammars
+
+A valid LR-item for a viable prefix has this structure:
+
+``` emacs-lisp
+(A B C L)
+```
+
+Example with grammar with production: S -> SaSb and S is non-terminal and a, b
are terminals. Look-ahead number: 1
+
+``` emacs-lisp
+(S nil (S a S b) (a))
+```
+
+* A is the production LHS
+* B, C is parts of the production RHS, if the dot is the left B is nil and C
is the entire RHS. If the dot is at the right then B is the production RHS and
C is nil, otherwise B and C contains parts of the RHS
+* L is the terminal look-ahead
+
#### Formal Shift-Reduce Parsing Algorithms
#### Simple Precedence Grammars
#### Extended Precedence Grammars
