objc/reader.m

   1 #import <Foundation/Foundation.h>
   2
   3 #import "types.h"
   4
   5 // Only used here, so define interface locally
   6 @interface Reader : NSObject
   7
   8 - (id)initWithTokens:(NSArray *)toks;
   9 - (id)init;
  10
  11 - (NSString *) next;
  12 - (NSString *) peek;
  13
  14 @end
  15
  16
  17 @implementation Reader
  18
  19 NSArray  *_tokens;
  20 int _position;
  21
  22 - (id)initWithTokens:(NSArray *)toks {
  23     self = [super init];
  24     if (self) {
  25         _tokens = toks;
  26         _position = 0;
  27     }
  28     return self;
  29 }
  30
  31 - (id)init {
  32     return [self initWithTokens:@[]];
  33 }
  34
  35 - (NSString *)next {
  36     _position++;
  37     return _tokens[_position-1];
  38 }
  39
  40 - (NSString *)peek {
  41     if ([_tokens count] > _position) {
  42         return _tokens[_position];
  43     } else {
  44         return nil;
  45     }
  46 }
  47
  48 @end
  49
  50
  51 NSArray * tokenize(NSString *str) {
  52     NSRegularExpression *regex = [NSRegularExpression
  53         regularExpressionWithPattern:@"[\\s,]*(~@|[\\[\\]{}()'`~^@]|\"(?:[\\\\].|[^\\\\\"])*\"?|;.*|[^\\s\\[\\]{}()'\"`@,;]+)"
  54         options:0
  55         error:NULL];
  56
  57     NSArray *matches = [regex
  58         matchesInString:str
  59         options:0
  60         range:NSMakeRange(0, [str length])];
  61
  62     NSMutableArray * tokens = [NSMutableArray array];
  63     for (NSTextCheckingResult *match in matches) {
  64         NSString * mstr = [str substringWithRange:[match rangeAtIndex:1]];
  65         if ([mstr characterAtIndex:0] == ';') { continue; }
  66         [tokens addObject:mstr];
  67     }
  68     return tokens;
  69 }
  70
  71 NSObject * read_atom(Reader * rdr) {
  72     NSRegularExpression *regex = [NSRegularExpression
  73         regularExpressionWithPattern:@"(^-?[0-9]+$)|(^-?[0-9][0-9.]*$)|(^nil$)|(^true$)|(^false$)|^\"((?:[\\\\].|[^\\\\\"])*)\"$|^\"(.*)$|:(.*)|(^[^\"]*$)"
  74         options:0
  75         error:NULL];
  76     NSNumberFormatter *numf = [[NSNumberFormatter alloc] init];
  77     numf.numberStyle = NSNumberFormatterDecimalStyle;
  78
  79     NSString *token = [rdr next];
  80
  81     NSArray *matches = [regex
  82         matchesInString:token
  83         options:0
  84         range:NSMakeRange(0, [token length])];
  85
  86     if ([matches count] > 0) {
  87
  88         NSTextCheckingResult *match = matches[0];
  89         if ([match rangeAtIndex:1].location < -1ULL/2) { // integer
  90             return [numf numberFromString:token];
  91         } else if ([match rangeAtIndex:2].location < -1ULL/2) { // float
  92             return [numf numberFromString:token];
  93         } else if ([match rangeAtIndex:3].location < -1ULL/2) { // nil
  94             return [NSNull alloc];
  95         } else if ([match rangeAtIndex:4].location < -1ULL/2) { // true
  96             return [MalTrue alloc]; // TODO: intern
  97         } else if ([match rangeAtIndex:5].location < -1ULL/2) { // false
  98             return [MalFalse alloc]; // TODO: intern
  99         } else if ([match rangeAtIndex:6].location < -1ULL/2) { // string
 100             NSString * str = [token substringWithRange:[match rangeAtIndex:6]];
 101             return [[[[str
 102                         stringByReplacingOccurrencesOfString:@"\\\\" withString:@"\u029e"]
 103                       stringByReplacingOccurrencesOfString:@"\\\"" withString:@"\""]
 104                      stringByReplacingOccurrencesOfString:@"\\n" withString:@"\n"]
 105                     stringByReplacingOccurrencesOfString:@"\u029e" withString:@"\\"];
 106         } else if ([match rangeAtIndex:7].location < -1ULL/2) { // string
 107             @throw @"read_atom: expected '\"', got EOF";
 108         } else if ([match rangeAtIndex:8].location < -1ULL/2) { // keyword
 109             return [NSString stringWithFormat:@"\u029e%@",
 110                     [token substringWithRange:[match rangeAtIndex:8]]];
 111         } else if ([match rangeAtIndex:9].location < -1ULL/2) { // symbol
 112             return [MalSymbol stringWithString:token];
 113         }
 114     }
 115
 116     @throw @"read_atom: invalid token";
 117 }
 118
 119 // Only used locally, so declare here
 120 NSObject * read_form(Reader * rdr);
 121
 122 NSArray * read_list(Reader * rdr, char start, char end) {
 123     NSString * token = [rdr next];
 124     NSMutableArray * ast = [NSMutableArray array];
 125
 126     if ([token characterAtIndex:0] != start) {
 127         @throw [NSString stringWithFormat:@"expected '%c'", start];
 128     }
 129     while ((token = [rdr peek]) && ([token characterAtIndex:0] != end)) {
 130         [ast addObject:read_form(rdr)];
 131     }
 132     if (!token) {
 133         @throw [NSString stringWithFormat:@"expected '%c', got EOF", end];
 134     }
 135     [rdr next];
 136     return ast;
 137 }
 138
 139 NSObject * read_form(Reader * rdr) {
 140     NSString *token = [rdr peek];
 141     switch ([token characterAtIndex:0]) {
 142     case '\'': [rdr next];
 143               return @[[MalSymbol stringWithString:@"quote"],
 144                        read_form(rdr)];
 145     case '`': [rdr next];
 146               return @[[MalSymbol stringWithString:@"quasiquote"],
 147                        read_form(rdr)];
 148     case '~': [rdr next];
 149               if ([token isEqualToString:@"~@"]) {
 150                   return @[[MalSymbol stringWithString:@"splice-unquote"],
 151                            read_form(rdr)];
 152               } else {
 153                   return @[[MalSymbol stringWithString:@"unquote"],
 154                            read_form(rdr)];
 155               }
 156     case '^': [rdr next];
 157               NSObject * meta = read_form(rdr);
 158               return @[[MalSymbol stringWithString:@"with-meta"],
 159                        read_form(rdr),
 160                        meta];
 161     case '@': [rdr next];
 162               return @[[MalSymbol stringWithString:@"deref"],
 163                        read_form(rdr)];
 164
 165     // lists
 166     case ')':
 167         @throw @"unexpected ')'";
 168     case '(':
 169         return read_list(rdr, '(', ')');
 170
 171     // vectors
 172     case ']':
 173         @throw @"unexpected ']'";
 174     case '[':
 175         return [MalVector fromArray:read_list(rdr, '[', ']')];
 176
 177     // hash maps
 178     case '}':
 179         @throw @"unexpected '}'";
 180     case '{':
 181         return hash_map(read_list(rdr, '{', '}'));
 182     default:
 183         return read_atom(rdr);
 184     }
 185 }
 186
 187 NSObject * read_str(NSString *str) {
 188     NSArray * tokens = tokenize(str);
 189     if ([tokens count] == 0) { @throw [NSException exceptionWithName:@"ReaderContinue"
 190                                        reason:@"empty token"
 191                                        userInfo:nil]; }
 192     //if ([tokens count] == 0) { @throw [[MalContinue alloc] init]; }
 193     return read_form([[Reader alloc] initWithTokens:tokens]);
 194 }