Start of EBNF parser

extra/peg/ebnf/authors.txt

@@ -0,0 +1 @@
+Chris Double

extra/peg/ebnf/ebnf-tests.factor

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+! Copyright (C) 2007 Chris Double.
+! See http://factorcode.org/license.txt for BSD license.
+!
+USING: kernel tools.test peg peg.ebnf ;
+IN: temporary
+
+{ T{ ebnf-non-terminal f "abc" } } [
+  "abc" 'non-terminal' parse parse-result-ast 
+] unit-test
+
+{ T{ ebnf-terminal f "55" } } [
+  "\"55\"" 'terminal' parse parse-result-ast 
+] unit-test
+
+! { } [
+!  "digit = \"0\" | \"1\" | \"2\"" 'rule' parse parse-result-ast
+! ] unit-test

extra/peg/ebnf/ebnf.factor

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+! Copyright (C) 2007 Chris Double.
+! See http://factorcode.org/license.txt for BSD license.
+USING: kernel arrays strings math.parser sequences namespaces peg ;
+IN: peg.ebnf
+
+TUPLE: ebnf-non-terminal symbol ;
+TUPLE: ebnf-terminal symbol ;
+TUPLE: ebnf-choice options ;
+
+C: <ebnf-non-terminal> ebnf-non-terminal
+C: <ebnf-terminal> ebnf-terminal
+C: <ebnf-choice> ebnf-choice
+
+GENERIC: ebnf-compile ( ast -- quot )
+
+M: ebnf-terminal ebnf-compile ( ast -- quot )
+  [
+    ebnf-terminal-symbol , \ token ,
+  ] [ ] make ;
+
+M: ebnf-choice ebnf-compile ( ast -- quot )
+  [
+    [
+      ebnf-choice-options [
+        ebnf-compile ,
+      ] each
+    ] { } make ,
+    [ call ] , \ map ,
+  ] [ ] make ;
+
+DEFER: 'rhs'
+
+: 'non-terminal' ( -- parser )
+  CHAR: a CHAR: z range repeat1 [ >string <ebnf-non-terminal> ] action ;
+
+: 'terminal' ( -- parser )
+  "\"" token hide [ CHAR: " = not ] satisfy repeat1 "\"" token hide 3array seq [ first >string <ebnf-terminal> ] action ;
+
+: 'element' ( -- parser )
+  'non-terminal' 'terminal' 2array choice ;
+
+: 'sequence' ( -- parser )
+  'element' sp repeat1 ;
+  
+: 'choice' ( -- parser )
+  'element' sp "|" token sp list-of [ <ebnf-choice> ] action ;
+
+: 'repeat0' ( -- parser )
+  "{" token sp hide
+  [ 'rhs' sp ] delay
+  "}" token sp hide 
+  3array seq ;
+
+: 'rhs' ( -- parser )
+  'repeat0'
+  'choice'
+  'sequence'
+  'element' 
+  4array choice ;
+  
+: 'rule' ( -- parser )
+  'non-terminal' 
+  "=" token sp 
+  'rhs' 
+  3array seq ;

extra/peg/ebnf/summary.txt

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+Grammar for parsing EBNF

extra/peg/peg.factor

@@ -216,3 +216,6 @@ PRIVATE>
 
 : delay ( parser -- parser )
   delay-parser construct-boa init-parser ;
+
+: list-of ( items separator -- parser )
+  hide over 2array seq repeat0 [ concat ] action 2array seq [ unclip 1vector swap first append ] action ;