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Very preliminary code.

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This commit is contained in:
Simon Brooke 2018-02-12 14:45:55 +00:00
parent 0a8e2a7664
commit d3cc5cb11f
10 changed files with 229 additions and 6 deletions
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6
src/squirrel_parse/core.clj Normal file
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(ns squirrel-parse.core)
(defn foo
"I don't do a whole lot."
[x]
(println x "Hello, World!"))

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src/squirrel_parse/parser.clj Normal file
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(ns ^{:doc "A very simple parser which parses production rules."
:author "Simon Brooke"}
squirrel-parse.parser
(:require [instaparse.core :as insta]
[clojure.string :refer [split trim triml]]))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;
;;;; squirrel-parse.parser: parse SQL into Clojure structures.
;;;;
;;;; This program is free software; you can redistribute it and/or
;;;; modify it under the terms of the GNU General Public License
;;;; as published by the Free Software Foundation; either version 2
;;;; of the License, or (at your option) any later version.
;;;;
;;;; This program is distributed in the hope that it will be useful,
;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;;;; GNU General Public License for more details.
;;;;
;;;; You should have received a copy of the GNU General Public License
;;;; along with this program; if not, write to the Free Software
;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
;;;; USA.
;;;;
;;;; Copyright (C) 2018 Simon Brooke
;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(def grammar
(str
"TABLE-SPEC := 'create' SPACE 'table' EXISTENCE SPACE NAME OPT-SPACE LPAR TABLE-SPEC-ELEMENTS RPAR ;
TABLE-SPEC-ELEMENTS := TABLE-SPEC-ELEMENT | TABLE-SPEC-ELEMENT COMMA TABLE-SPEC-ELEMENTS ;
TABLE-SPEC-ELEMENT := COLUMN-SPEC | TABLE-CONSTRAINT ;
COLUMN-SPEC := NAME SPACE DATATYPE | COLUMN-SPEC SPACE COLUMN-CONSTRAINTS ;
TABLE-CONSTRAINT := 'foo' ;
COLUMN-CONSTRAINTS := COLUMN-CONSTRAINT | COLUMN-CONSTRAINT SPACE COLUMN-CONSTRAINT ;
COLUMN-CONSTRAINT := 'constraint' SPACE NAME COLUMN-CONSTRAINT | NOT-NULL-CC | NULL-CC | DEFAULT-CC | UNIQUE-CC | PRIMARY-CC | REFERENCES-CC ;
NOT-NULL-CC := 'not' SPACE 'null' ;
NULL-CC := 'null' ;
DEFAULT-CC := 'default' SPACE EXPR ;
UNIQUE-CC := 'unique' SPACE INDEX-PARAMS ;
PRIMARY-CC := 'primary' SPACE 'key' INDEX-PARAMS ;
REFERENCES-CC := 'references' SPACE NAME SPACE LPAR NAMES RPAR REF-DIRECTIVES ;
REF-DIRECTIVES := '' | REF-DIRECTIVE SPACE REF-DIRECTIVES ;
REF-DIRECTIVE := REF-MATCH | REF-ON-UPDATE | REF-ON-DELETE ;
REF-MATCH := 'match' SPACE MATCH-TYPE ;
REF-ON-DELETE := 'on' SPACE 'delete' SPACE REF-ACTION ;
REF-ON-UPDATE := 'on' SPACE 'update' SPACE REF-ACTION ;
MATCH-TYPE := 'full' | 'partial' | 'simple' ;
INDEX-PARAMS := '' ;
REF-ACTION := 'no' SPACE 'action' | 'restrict' | 'cascade' | 'set' SPACE 'null' | 'set' SPACE 'default';
EXPR := 'foo' ; "
;; there are some things we ignore
"EXISTENCE := SPACE 'if' SPACE 'not' SPACE 'exists' | '' ;
COMMENT := #'--[~\\n\\r]*' ;"
"DATATYPE := 'integer' | 'float' | 'char' LPAR INT-VAL RPAR | 'varchar' LPAR INT-VAL RPAR | 'text' ;
INT-VAL := #'[0-9]+' ;"
;; there don't seem to be any valid cases where a comma may not be either preceded or succeeded by white-space
"COMMA := OPT-SPACE ',' OPT-SPACE ;
LPAR := OPT-SPACE '(' OPT-SPACE ;
RPAR := OPT-SPACE ')' OPT-SPACE ; "
;; OPT-SPACE is optional space - it's acceptable as OPT-SPACE if there are no whitespace characters. Comments are
;; also acceptable wherever OPT-SPACE is acceptable
"OPT-SPACE := #'\\s*' | OPT-SPACE COMMENT OPT-SPACE;"
;; SPACE is mandatory white-space; comments are acceptable here too but there must be a real space character
"SPACE := #'\\s+' | OPT-SPACE SPACE | SPACE OPT-SPACE ;
NAMES := NAME | NAME COMMA NAMES ;
NAME := #'[a-zA-Z][a-zA-Z0-9_]*'"))
(defn ignorable?
"True if `x` is something which just clutters up the parse tree."
[x]
(and
(coll? x)(contains? #{:SPACE :OPT-SPACE :COMMENT} (first x))))
(defn remove-recursive
"Return a collection like this `collection` from which items which are matched
by this `predicate` have been removed at all levels."
[predicate collection]
(map
#(if
(coll? %)
(remove-recursive predicate %)
%)
(remove predicate collection)))
(def parse
"Parse the argument, assumed to be a string in the correct syntax, and return a parse tree."
(insta/parser grammar))