checkpoint

TODO

@@ -3,11 +3,11 @@
 * parsing posix shell: nested "'""'": done
 * globbing: done
 * job control: done
-* readline: prompt2: done?
-* pipe: almost done: mix built-in with process
+* substitution: done
+* readline: prompt2: in progress
+* pipe: in progress: mix built-in with process
 * compound: case, while, until
-* expansion
-* substitution
-* alias
+* expansion: done
+* alias:
 * redirection:
 * posix compliance:

gash/gash.scm

@@ -20,11 +20,27 @@
 
   :export (main))
 
+(define (remove-shell-comments s)
+  (string-join (map
+                (lambda (s)
+                  (let* ((n (string-index s #\#)))
+                    (if n (string-pad-right s (string-length s) #\space  0 n)
+                        s)))
+                (string-split s #\newline)) "\n"))
+
+(define (remove-escaped-newlines s)
+  (reduce (lambda (next prev)
+            (let* ((escaped? (string-suffix? "\\" next))
+                   (next (if escaped? (string-drop-right next 1) next))
+                   (sep (if escaped? "" "\n")))
+              (string-append prev sep next)))
+          "" (string-split s #\newline)))
+
 (define (file-to-string filename)
-  ((compose read-string open-input-file)  filename))
+  ((compose read-string open-input-file) filename))
 
 (define (string-to-ast string)
-  ((compose parse remove-shell-comments) string))
+  ((compose parse remove-escaped-newlines remove-shell-comments) string))
 
 (define (file-to-ast filename)
   ((compose string-to-ast file-to-string) filename))
@@ -48,8 +64,16 @@ the GNU Public License, see COPYING for the copyleft.
 
 "))
 
+(define global-variables '())
+
 (define (main args)
   (setenv "PATH" "/bin:/usr/bin:/sbin:/usr/sbin:.")
+  (map (lambda (key-value)
+         (let* ((key-value (string-split key-value #\=))
+                (key (car key-value))
+                (value (cadr key-value)))
+           (set! global-variables (assoc-set! global-variables key value))))
+       (environ))
   (let ((thunk
          (lambda ()
            (job-control-init)
@@ -99,14 +123,6 @@ the GNU Public License, see COPYING for the copyleft.
                   (newline)))))))
     (thunk)))
 
-(define (remove-shell-comments s)
-  (string-join (map
-                (lambda (s)
-                  (let* ((n (string-index s #\#)))
-                    (if n (string-pad-right s (string-length s) #\space  0 n)
-                        s)))
-                (string-split s #\newline)) "\n"))
-
 (define (expand identifier o) ;;identifier-string -> symbol
   (define (expand- o)
     (let ((dollar-identifier (string-append "$" identifier)))
@@ -199,10 +215,12 @@ the GNU Public License, see COPYING for the copyleft.
     (('do-group "do" (command "done")) (transform command))
     (('pipeline command) (let* ((command (transform command))) (or (builtin command) `(pipeline #t ,@command))))
     (('pipeline command piped-commands) `(pipeline #t ,@(transform command) ,@(transform piped-commands)))
+    (('simple-command ('word (assignment name value))) (set! global-variables (assoc-set! global-variables (transform name) (transform value))) #t)
     (('simple-command ('word s)) `((glob ,(transform s))))
     (('simple-command ('word s1) ('io-redirect "<<" ('here-document s2))) `((append (glob "echo") (cons "-n" (glob ,s2))) (glob ,(transform s1))))
     (('simple-command ('word s1) ('word s2)) `((append (glob ,(transform s1)) (glob ,(transform s2)))))
     (('simple-command ('word s1) (('word s2) ...)) `((append (glob ,(transform s1)) (append-map glob (list ,@(map transform s2))))))
+    (('variable s) (assoc-ref global-variables (string-drop s 1)))
     (('literal s) (transform s))
     (('singlequotes s) (string-concatenate `("'" ,s "'")))
     (('doublequotes s) (string-concatenate `("\"" ,s "\"")))

gash/io.scm

@@ -2,7 +2,7 @@
 
   :export (stdout stderr))
 
-(define (output port . o)
+(define (output port o)
   (map (lambda (o) (display o port)) o)
   (newline port)
   (force-output port))

gash/peg.scm

@@ -54,8 +54,8 @@
      for-clause       <-- 'for' (sp+ identifier (ws+ 'in' expression sequential-sep / sp* sequential-sep) do-group / error)
      expression       <-- sp+ substitution sp* / (sp+ word)* sp*
      do-group         <-- 'do' ws* (ne-compound-list 'done' / error)
-     if-clause        <-- 'if' (ne-compound-list 'then' ne-compound-list else-part? 'fi' / error)
-     else-part        <-- 'elif' (ne-compound-list 'then' ne-compound-list else-part? / error) / 'else' (ne-compound-list / error)
+     if-clause        <-- 'if' (ne-compound-list 'then' ws* ne-compound-list else-part? 'fi' / error)
+     else-part        <-- 'elif' (ne-compound-list 'then' ws* ne-compound-list else-part? / error) / 'else' (ne-compound-list / error)
      while-clause     <-- 'while' (ne-compound-list do-group / error)
      until-clause     <-- 'until' (ne-compound-list do-group / error)
      function-def     <-- name sp* '(' sp* ')' ws* (function-body / error)
@@ -78,7 +78,7 @@
      ltest            <   '[ '
      rtest            <   ' ]'
      substitution     <-- ('$(' (script ')' / error)) / ('`' (script '`' / error))
-     assignment       <-- name assign word?
+     assignment       <-- name assign (substitution / word)?
      assign           <   '='
      literal          <-- (variable / delim / (![0-9] (![()] !io-op !sp !nl !break !pipe !assign .)+) / ([0-9]+ &separator)) literal*
      variable         <-- '$' ('$' / '*' / '@' / [0-9] / identifier / ([{] (![}] .)+ [}]))

test/assignment

@@ -0,0 +1 @@
+SHELL=/bin/bash

test/for

@@ -1 +1 @@
-for f in *; do echo $f | grep c; done
+for f in *; do echo "$f:" | grep c; done

test/test

@@ -0,0 +1,3 @@
+foo=bar
+bar=foo
+if [ "${foo}" != "foo" -a "${bar}" != "bar" ]; then echo foobar; fi

test/var

@@ -0,0 +1 @@
+echo $SHELL