117 lines
2.6 KiB
R
117 lines
2.6 KiB
R
#include "Cons.h"
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#include "Parser.h"
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#include "Nil.h"
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#include "Error.h"
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#include "defs.h"
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@implementation Parser
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+ (id) newFromSource: (string) s file: (string) f
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{
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return [[self alloc] initWithSource: s file: f];
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}
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- (id) initWithSource: (string) s file: (string) f
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{
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self = [super init];
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lexer = [Lexer newFromSource: s file: f];
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file = f;
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return self;
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}
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- (SchemeObject*) readList
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{
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local SchemeObject *token, *res;
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local int line;
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local Error *err;
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line = [lexer lineNumber];
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token = [self readAtomic];
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if ([token isError])
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return token;
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if (!token) {
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err = [Error type: "parse" message: "Unmatched open parenthesis"];
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[err source: file];
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[err line: [lexer lineNumber]];
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return err;
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}
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if (token == [Symbol rightParen]) {
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return [Nil nil];
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} else if (token == [Symbol dot]) {
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res = [self readAtomic];
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if ([res isError]) return res;
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if ([self readAtomic] != [Symbol rightParen]) {
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err = [Error type: "parse" message: "Improper use of dot"];
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[err source: file];
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[err line: [lexer lineNumber]];
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return err;
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}
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return res;
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} else {
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res = [self readList];
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if ([res isError]) return res;
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res = cons(token, res);
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[res source: file];
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[res line: line];
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return res;
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}
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}
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- (SchemeObject*) readAtomic
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{
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local SchemeObject *token, *list, *res;
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local int line;
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line = [lexer lineNumber];
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token = [lexer nextToken];
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if ([token isError]) {
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return token;
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}
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if (!token) {
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return nil;
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}
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if (token == [Symbol leftParen]) {
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list = [self readList];
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return list;
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} else if (token == [Symbol quote]) {
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res = [self read];
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if ([res isError]) return res;
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res = cons(res, [Nil nil]);
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[res source: file];
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[res line: line];
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res = cons([Symbol forString: "quote"], res);
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[res source: file];
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[res line: line];
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return res;
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} else return token;
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}
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- (SchemeObject*) read
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{
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local SchemeObject *token;
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local Error *err;
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token = [self readAtomic];
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if (token == [Symbol rightParen]) {
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err = [Error type: "parse" message: "mismatched close parentheis"];
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[err source: file];
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[err line: [lexer lineNumber]];
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return err;
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}
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return token;
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}
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- (void) markReachable
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{
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[lexer mark];
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}
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@end
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