diff options
-rw-r--r-- | input.lisp | 11 | ||||
-rw-r--r-- | monparser.asd | 3 | ||||
-rw-r--r-- | notes.md | 22 | ||||
-rw-r--r-- | package.lisp | 23 | ||||
-rw-r--r-- | parser.lisp | 55 |
5 files changed, 64 insertions, 50 deletions
@@ -1,4 +1,4 @@ -(in-package #:input) +(in-package #:monparser) (defclass input () ((cursor :initarg :cursor :accessor cursor :initform 0) @@ -28,8 +28,15 @@ (defun from-string (str) (make-instance 'input :data str)) +(defun read-file (path) + (with-open-file (file path) + (let* ((size (file-length file)) + (buf (make-string size))) + (read-sequence buf file) + buf))) + (defun from-file (filename) - (make-instance 'input :file filename :data (str:read-file filename))) + (make-instance 'input :file filename :data (read-file filename))) (defun line-and-column (input) (let ((line 1) (column 1)) diff --git a/monparser.asd b/monparser.asd index 6374e8e..2aa7290 100644 --- a/monparser.asd +++ b/monparser.asd @@ -1,6 +1,5 @@ -(asdf:defsystem #:monparser +(defsystem #:monparser :serial t - :depends-on (#:utils) :components ((:file "package") (:file "input") diff --git a/notes.md b/notes.md new file mode 100644 index 0000000..9eddec5 --- /dev/null +++ b/notes.md @@ -0,0 +1,22 @@ +# Problem +When in a one-of block, it's harder to tell where an error came from. + +# Current solution +We have critical blocks that stop parsing when the parser inside fails. + +# Problem with current solution +We need to be dilligent in placing critical blocks. + +# Another approach +We could take a page from LR parsers and instead of driving the parsing from the parsers themselves we invert the flow, making the input drive the parsing. This results in a breadth first parsing, where the one-of block parses one step of every of it's children and decides which to keep. In the event there's only one children left, it is critical, so a failure stops parsing and reports the error. + +# How to select between BF and DF when parsing +Add an extra argument to parser type (lambda (input)) for the parsing mode. +one-of will be BF and comp will be DF. +This means that the immediate children of a one-of block will be parsed step by step. + +# Implementing BF in bind +Instead of calling the resulting function with the input, return it. +It will be the caller's responsibility to call the resulting lambda with the appropiate input. +This will give control to the one-of block to call the next parsing step. + diff --git a/package.lisp b/package.lisp index 4cdb68f..deae22c 100644 --- a/package.lisp +++ b/package.lisp @@ -1,27 +1,10 @@ -(defpackage #:input +(defpackage #:monparser (:use #:cl) - (:export #:file - #:data - #:cursor - #:line-and-column - #:has-data? - #:prefix? - #:peek - #:advance - #:from-string - #:from-file)) - -(defpackage #:parser - (:use #:cl) - (:export #:run - #:parsing-tree - #:parsing-left - #:failure-place - #:failure-message + (:export #:parse-file + #:parse-string #:crit #:comp #:one-of - #:all-of #:unit #:literal #:nothing diff --git a/parser.lisp b/parser.lisp index 82f619e..ca13598 100644 --- a/parser.lisp +++ b/parser.lisp @@ -1,7 +1,13 @@ -(in-package #:parser) +(in-package #:monparser) -(defun run (p input) - (let ((result (funcall p input))) +(defun parse-string (p input) + (let ((result (funcall p (from-string input)))) + (if (parsing-p result) + (parsing-tree result) + result))) + +(defun parse-file (p input) + (let ((result (funcall p (from-file input)))) (if (parsing-p result) (parsing-tree result) result))) @@ -15,19 +21,17 @@ message) (defmethod print-object ((obj failure) stream) - (let ((file (input:file (failure-place obj)))) + (let ((file (file (failure-place obj)))) (if file - (multiple-value-bind (line column) (input:line-and-column (failure-place obj)) + (multiple-value-bind (line column) (line-and-column (failure-place obj)) (format stream "~a:~a:~a: ~a" line column file (failure-message obj))) - (format stream "~a: ~a" (input:cursor (failure-place obj)) (failure-message obj))))) + (format stream "~a: ~a" (cursor (failure-place obj)) (failure-message obj))))) (defun new (tree) (lambda (input) (make-parsing :tree tree :left input))) (defun bind-with-input (p f) - (declare (optimize (speed 3)) - (function p f)) (lambda (input) (let ((r (funcall p input))) (if (parsing-p r) @@ -36,8 +40,6 @@ r)))) (defun bind (p f) - (declare (optimize (speed 3)) - (function p f)) (lambda (input) (let ((r (funcall p input))) (if (parsing-p r) @@ -46,8 +48,6 @@ r)))) (defun discarding-bind (p f) - (declare (optimize (speed 3)) - (function p f)) (lambda (input) (let ((r (funcall p input))) (if (parsing-p r) @@ -103,19 +103,19 @@ (and (symbolp x) (string-equal (symbol-name x) "IT"))) predicate)))) `(lambda (input) - (if (input:has-data? input) - (let ((it (input:peek input))) + (if (has-data? input) + (let ((it (peek input))) (if ,predicate - (make-parsing :tree it :left (input:advance input)) + (make-parsing :tree it :left (advance input)) (make-failure :place input :message (format nil "Expected: ~a, Got: ~a" ',predicate it)))) (make-failure :place input :message "Reached end of input.")))) (defun literal (target) (lambda (input) - (if (input:has-data? input) - (if (input:prefix? target input) - (make-parsing :tree target :left (input:advance input (length target))) + (if (has-data? input) + (if (prefix? target input) + (make-parsing :tree target :left (advance input (length target))) (make-failure :place input :message "Predicate not satisfied.")) (make-failure :place input :message "Reached end of input.")))) @@ -128,22 +128,25 @@ (defun many (p) (comp ((x p) (xs (optional (many p)))) - (cons x xs))) + (cons x xs))) (defun repeat (p min &optional (max 0)) (if (> min 0) (comp ((x p) (xs (repeat p (1- min) (1- max)))) - (cons x xs)) + (cons x xs)) (if (> max 0) (comp ((x (optional p)) (xs (repeat p 0 (if x (1- max) 0)))) - (if x (cons x xs) x)) + (if x (cons x xs) x)) nothing))) +(defun whitespace? (x) + (some (lambda (y) (char= x y)) '(#\Space #\Newline #\Tab))) + (defparameter whitespace - (comp ((_ (optional (many (unit char:whitespace?))))) - nil)) + (comp ((_ (optional (many (unit whitespace?))))) + nil)) (defun separated-list (p separator &key include-separator) (comp ((v p) @@ -151,6 +154,6 @@ (vn (if sep (crit (separated-list p separator)) nothing))) - (if include-separator - (cons v (cons sep vn)) - (cons v vn)))) + (if include-separator + (cons v (cons sep vn)) + (cons v vn)))) |