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#include "stdlib.lisp"
; string -> string
(define string-escape (str)
(let ((hexdigit (lambda (n) (substr n 1 "0123456789abcdef")))
(go (lambdarec rec (str yet)
(if (= str "") yet
(let ((ch (substr 0 1 str))
(n (ord ch))
(out (cond
(= ch "\n") "\\n"
(= ch "\r") "\\r"
(= ch "\t") "\\t"
(= ch "\0") "\\0"
(= ch "\"") "\\\""
(= ch "\\") "\\\\"
(< n 32) (concat "\\x" (hexdigit (/ n 16)) (hexdigit (mod n 16)))
ch)))
(rec (substr 1 -1 str) (concat yet out)))))))
(go str "")))
; tag string -> string
(define ansi-color (clr str)
(let ((style (cond
(= clr 'red) "31"
(= clr 'green) "32"
(= clr 'yellow) "33"
(= clr 'blue) "34"
(= clr 'cyan) "36"
(error "Unknown color in ansi-color" clr))))
(concat "\x1B[" style "m" str "\x1B[0m")))
; char string -> bool
(define str-elem (ch str)
(if (= str "") 0
(if (= ch (substr 0 1 str)) 1
(str-elem ch (substr 1 -1 str)))))
; char -> bool
(define isspace? (ch)
(str-elem ch " \n\t\r"))
; char -> bool
(define isdigit? (ch)
(let ((n (ord ch))) (and (<= 48 n) (<= n 57))))
; char -> bool
(define lowercase? (ch)
(let ((n (ord ch))) (and (<= 97 n) (<= n 122))))
; char -> bool
(define uppercase? (ch)
(let ((n (ord ch))) (and (<= 65 n) (<= n 90))))
; char -> bool
(define iswordchar? (ch)
(or (str-elem ch "-_?+/*!=<>.")
(or (lowercase? ch) (uppercase? ch))))
; char -> bool
(define isrestwordchar? (ch)
(or (iswordchar? ch) (isdigit? ch)))
; string -> int (does not perform any checking)
(define parse-int (str)
(let ((helper (lambdarec rec (str n)
(let ((ch (substr 0 1 str))
(rest (substr 1 -1 str)))
(if (isdigit? ch)
(rec rest (+ (* 10 n) (- (ord ch) 48)))
n)))))
(helper str 0)))
; char -> int
(define parse-hex-digit (ch)
(let ((n (ord ch)))
(cond
(and (<= 48 n) (<= n 57))
(- n 48)
(and (<= 97 n) (<= n 102))
(- n 87)
(and (<= 65 n) (<= n 70))
(- n 55)
(error "Invalid hex escape digit " ch))))
; string -> (string[parsed escape] string[rest])
(define parse-string-escape (str)
(let ((ch (substr 0 1 str)))
(cond
(= ch "n")
(list "\n" (substr 1 -1 str))
(= ch "r")
(list "\r" (substr 1 -1 str))
(= ch "t")
(list "\t" (substr 1 -1 str))
(= ch "0")
(list "\0" (substr 1 -1 str))
(= ch "\"")
(list "\"" (substr 1 -1 str))
(= ch "\\")
(list "\\" (substr 1 -1 str))
(= ch "x")
(let ((h1 (parse-hex-digit (substr 1 1 str)))
(h2 (parse-hex-digit (substr 2 1 str))))
(list (chr (+ (* 16 h1) h2)) (substr 3 -1 str)))
(error "Invalid string escape character " ch))))
; string[input] string[string to prepend to result] -> (string[parsed till bare "] string[rest])
(define parse-string-contents (str yet)
(let ((ch (substr 0 1 str))
(rest (substr 1 -1 str)))
(cond
(= ch "")
(error "Non-terminated string in source")
(= ch "\"")
(list yet rest)
(= ch "\\")
(let ((pair (parse-string-escape rest)))
(parse-string-contents (cadr pair) (concat yet (car pair))))
(parse-string-contents rest (concat yet ch)))))
; deftype token = ('tag <field>), where the type of <field> depends on the tag
; ('open '()) ('close '()) ('quote '()) ('string "text") ('number 123) ('name "name") ('include "path")
; string -> (token string[rest])
(define next-token (str)
(let ((ch (substr 0 1 str))
(rest (substr 1 -1 str)))
(cond
(= ch "")
'()
(isspace? ch)
(next-token rest)
(= ch ";")
(next-token (drop-while (lambda (c) (not (= c "\n"))) rest))
(= ch "(")
(list (list 'open '()) rest)
(= ch ")")
(list (list 'close '()) rest)
(= ch "'")
(list (list 'quote '()) rest)
(= ch "#")
(if (= (substr 0 7 rest) "include")
(let ((pair (next-token (substr 7 -1 rest))))
(cond
(null? pair)
(error "Expected path after #include")
(= (car (car pair)) 'string)
(list (list 'include (cadr (car pair))) (cadr pair))
(error "Expected string after #include")))
(error "Unknown preprocessor directive after '#'"))
(= ch "\"")
(let ((pair (parse-string-contents rest ""))
(text (car pair))
(rest2 (cadr pair)))
(list (list 'string text) rest2))
(or (iswordchar? ch) (isdigit? ch))
(let ((restword (take-while isrestwordchar? rest))
(rest2 (substr (length restword) -1 rest)))
(if (and (all isdigit? restword)
(or (isdigit? ch) (and (= ch "-") (> (length restword) 0))))
(list (list 'number (parse-int (concat ch restword))) rest2)
(list (list 'name (concat ch restword)) rest2)))
(error "Invalid token" ch))))
; string -> (list token...)
(define tokenise (str)
(let ((helper (lambdarec rec (str2 rev-prefix)
(let ((pair (next-token str2)))
(if (null? pair)
(reverse rev-prefix)
(let ((token (car pair))
(rest (cadr pair)))
(rec rest (cons token rev-prefix))))))))
(helper str '())))
; token -> string
(define pretty-token (token)
(let ((tag (car token))
(field (cadr token)))
(cond
(= tag 'open)
(ansi-color 'red "(")
(= tag 'close)
(ansi-color 'red ")")
(= tag 'quote)
(ansi-color 'green "'")
(= tag 'string)
(ansi-color 'yellow (concat "\"" (string-escape field) "\""))
(= tag 'number)
(ansi-color 'blue (number->string field))
(= tag 'name)
field
(= tag 'include)
(concat (ansi-color 'cyan "#include") " " (ansi-color 'yellow (concat "\"" (string-escape field) "\"")))
(error "Invalid token tag in pretty-token" tag))))
; tokens -> string
(define pretty-token-list (tokens)
(if (null? tokens)
""
(concat (pretty-token (car tokens)) " " (pretty-token-list (cdr tokens)))))
; (define logged-token-fn (name fn)
; (lambda (x)
; (do
; (print name (pretty-token-list x))
; (let ((res (fn x)))
; (do
; (print "->" name (car res) (pretty-token-list (cadr res)))
; res)))))
(define logged-token-fn (name fn) fn)
(declare parse-sexpr)
; deftype item = ('tag <field>), where the type of <field> depends on the tag
; ('string "text") ('number 123) ('name "name") ('quote item) ('sexpr (list item...)) ('include "path")
; tokens -> (item tokens[rest])
(define parse-item (logged-token-fn "parse-item" (lambda (tokens)
(if (null? tokens)
(error "Expected value, not end-of-file")
(let ((tag (car (car tokens))))
(cond
(= tag 'open)
(parse-sexpr tokens)
(= tag 'close)
(error "Unexpected close parenthesis")
(= tag 'quote)
(let ((pair (parse-item (cdr tokens))))
(list (list 'quote (car pair)) (cadr pair)))
(= tag 'string)
(list (car tokens) (cdr tokens))
(= tag 'number)
(list (car tokens) (cdr tokens))
(= tag 'name)
(list (car tokens) (cdr tokens))
(= tag 'include)
(list (car tokens) (cdr tokens))
(error "Invalid token tag?")))))))
; tokens -> (list[items] tokens[rest])
(define parse-items (logged-token-fn "parse-items" (lambda (tokens)
(cond
(null? tokens)
(list '() '())
(= (car (car tokens)) 'close)
(list '() tokens)
(let ((item-pair (parse-item tokens)))
(if (null? item-pair)
(error "??? () from parse-item?")
(let ((items-pair (parse-items (cadr item-pair))))
(list (cons (car item-pair) (car items-pair)) (cadr items-pair)))))))))
; tokens -> (list[items] tokens[rest])
(define parse-sexpr (logged-token-fn "parse-sexpr" (lambda (tokens)
(if (null? tokens)
'()
(if (!= (car (car tokens)) 'open)
(error "Expected s-expression")
(let ((items-pair (parse-items (cdr tokens)))
(items (car items-pair))
(rest (cadr items-pair)))
(if (null? rest)
(error "Missing close parenthesis at end of file")
(if (!= (car (car rest)) 'close)
(error "Expected close parenthesis to end sexpr")
(list (list 'list items) (cdr rest))))))))))
; tokens -> list[items]
(define parse-program (tokens)
(let ((pair (parse-items tokens))
(items (car pair))
(rest (cadr pair)))
(if (not (null? rest))
(error "??? Unrecognised extra tokens at end of file")
(cons 'program items))))
; ast -> string
(define pretty-ast-compact (ast)
(cond
(= (car ast) 'program)
(intercalate " " (map pretty-ast-compact (cdr ast)))
(= (car ast) 'list)
(concat "(" (intercalate " " (map pretty-ast-compact (cadr ast))) ")")
(= (car ast) 'quote)
(concat "'" (pretty-ast-compact (cadr ast)))
(= (car ast) 'string)
(pretty-token ast)
(= (car ast) 'number)
(pretty-token ast)
(= (car ast) 'name)
(pretty-token ast)
(= (car ast) 'include)
(pretty-token ast)
(error "Unrecognised AST type in pretty-ast-compact" (car ast))))
; ast -> string
(define pretty-ast (ast)
(let ((isnotnl? (lambda (ch) (!= ch "\n")))
(indent (lambdarec rec (str)
(let ((line (take-while isnotnl? str))
(rest (drop-while isnotnl? str)))
(if (= rest "")
line
(concat line "\n " (rec (substr 1 -1 rest)))))))
(indent-items (lambdarec rec (items)
(if (null? items)
""
(concat
(indent (pretty-ast (car items)))
(concat-list
(map (lambda (i) (concat "\n " (indent (pretty-ast i))))
(cdr items)))))))
(print-program (lambdarec rec (items)
(if (null? items)
""
(concat
(pretty-ast (car items))
(concat-list
(map (lambda (i) (concat "\n" (pretty-ast i)))
(cdr items))))))))
(cond
(= (car ast) 'program)
(print-program (cdr ast))
(= (car ast) 'list)
(concat "(" (indent-items (cadr ast)) ")")
(= (car ast) 'quote)
(concat "'" (pretty-ast-compact (cadr ast)))
(= (car ast) 'string)
(pretty-token ast)
(= (car ast) 'number)
(pretty-token ast)
(= (car ast) 'name)
(pretty-token ast)
(= (car ast) 'include)
(pretty-token ast)
(error "Unrecognised AST type in pretty-ast" (car ast)))))
(let ((tokens (tokenise (read-file "tests/lispparser.lisp"))))
(do
; (print (pretty-token-list tokens))
; (print (parse-program tokens))
(print (pretty-ast (parse-program tokens)))))
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