peg can now be used for parsing words

basis/peg-lexer/peg-lexer.factor

@@ -0,0 +1,53 @@
+USING: hashtables assocs sequences locals math accessors multiline delegate strings
+delegate.protocols kernel peg peg.ebnf lexer namespaces combinators parser words ;
+IN: peg-lexer
+
+TUPLE: lex-hash hash ;
+CONSULT: assoc-protocol lex-hash hash>> ;
+: <lex-hash> ( a -- lex-hash ) lex-hash boa ;
+
+: pos-or-0 ( neg? -- pos/0 ) dup 0 < [ drop 0 ] when ;
+
+:: store-pos ( v a -- )
+   [let | n [ input a at v head-slice ] |
+      v "\n" n last-index 0 or - lexer get (>>column)
+      n [ "\n" = ] filter length 1 + lexer get (>>line) ] ;
+
+M: lex-hash set-at swap {
+   { pos [ store-pos ] }
+   [ swap hash>> set-at ] } case ;
+
+:: at-pos ( t l c -- p ) t l 1 - head-slice [ length ] map sum pos-or-0 c + ;
+
+M: lex-hash at* swap {
+      { input [ drop lexer get text>> "\n" join t ] }
+      { pos [ drop lexer get [ text>> ] [ line>> ] [ column>> ] tri at-pos t ] }
+      [ swap hash>> at* ] } case ;
+
+: with-global-lexer ( quot -- result )
+   [ f lrstack set
+        V{ } clone error-stack set H{ } clone \ heads set
+        H{ } clone \ packrat set ] f make-assoc <lex-hash>
+   swap bind ; inline
+
+! Usage:
+! ON-BNF: word expr= [1-9] ;ON-BNF
+! << name parser create-bnf >>
+
+: parse* ( parser -- ast ) compile
+   [ execute [ error-stack get first throw ] unless* ] with-global-lexer
+   ast>> ;
+
+: create-bnf ( name parser -- ) [ lexer get skip-blank parse* dup V{ } = [ parsed ] unless ] curry
+    define POSTPONE: parsing ;
+
+: ON-BNF: CREATE-WORD reset-tokenizer ";ON-BNF" parse-multiline-string parse-ebnf
+    main swap at reset-tokenizer create-bnf ; parsing
+
+! Tokenizer like standard factor lexer
+EBNF: factor
+space = " " | "\n" | "\t"
+spaces = space* => [[ drop ignore ]]
+chunk = (!(space) .)+ => [[ >string ]]
+expr = spaces chunk
+;EBNF