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Further refactoring done. The Parser runs without crashing, however it's output is still to be checked and verified.

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This commit is contained in:
glm94
2022-03-02 21:24:58 +00:00
parent e20ccb8cfb
commit 221d575c16
6 changed files with 85 additions and 64 deletions
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lox.c
+4 -1
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@@ -1,4 +1,6 @@
#include "scanner.h" #include "scanner.h"
#include "parser.h"
#include "expr.h"
#include <stdio.h> #include <stdio.h>
#include <stdlib.h> #include <stdlib.h>
#include <sysexits.h> #include <sysexits.h>
@@ -37,7 +39,8 @@ void RunFile(const char* path) {
TokenList* tokens = ScanTokens(contents); TokenList* tokens = ScanTokens(contents);
free(contents); free(contents);
Print(tokens); Print(tokens);
Expr* tree = GenerateExpressionTree(tokens);
FreeExpressionTree(tree);
DestroyTokenList(tokens); DestroyTokenList(tokens);
} }
parser.c
+41 -30
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@@ -7,13 +7,12 @@ Expr* Term(void);
Expr* Factor(void); Expr* Factor(void);
Expr* Unary(void); Expr* Unary(void);
Expr* Primary(void); Expr* Primary(void);
int SMatch(int, ...); int Match(int, ...);
int Check(TokenType); int Check(TokenType);
int SIsAtEnd(void); int ParserAtEnd(void);
Token* SPeek(void); Token* ParserPeek(void);
Token* Previous(void); Token* Previous(void);
Token* SAdvance(void); Token* AdvanceParser(void);
//Token* CreateToken(char*, TokenType);
const TokenList* ListOfTokens; const TokenList* ListOfTokens;
int Current = 0; int Current = 0;
@@ -32,7 +31,7 @@ Expr* Expression() {
Expr* Equality() { Expr* Equality() {
Expr* expr = Comparison(); Expr* expr = Comparison();
while(SMatch(2, Bang_Equal, Equal_Equal)) { while(Match(2, Bang_Equal, Equal_Equal)) {
Token* operator = Previous(); Token* operator = Previous();
Expr* right = Comparison(); Expr* right = Comparison();
Expr* temp = calloc(1, sizeof(Expr)); Expr* temp = calloc(1, sizeof(Expr));
@@ -49,7 +48,7 @@ Expr* Equality() {
Expr* Comparison() { Expr* Comparison() {
Expr* expr = Term(); Expr* expr = Term();
while(SMatch(4, Greater, Greater_Equal, Less, Less_Equal)) { while(Match(4, Greater, Greater_Equal, Less, Less_Equal)) {
Token* operator = Previous(); Token* operator = Previous();
Expr* right = Term(); Expr* right = Term();
Expr* temp = calloc(1, sizeof(Expr)); Expr* temp = calloc(1, sizeof(Expr));
@@ -66,7 +65,7 @@ Expr* Comparison() {
Expr* Term() { Expr* Term() {
Expr* expr = Factor(); Expr* expr = Factor();
while(SMatch(2, Minus, Plus)) { while(Match(2, Minus, Plus)) {
Token* operator = Previous(); Token* operator = Previous();
Expr* right = Factor(); Expr* right = Factor();
Expr* temp = calloc(1, sizeof(Expr)); Expr* temp = calloc(1, sizeof(Expr));
@@ -83,7 +82,7 @@ Expr* Term() {
Expr* Factor() { Expr* Factor() {
Expr* expr = Unary(); Expr* expr = Unary();
while(SMatch(2, Slash, Star)) { while(Match(2, Slash, Star)) {
Token* operator = Previous(); Token* operator = Previous();
Expr* right = Unary(); Expr* right = Unary();
Expr* temp = calloc(1, sizeof(Expr)); Expr* temp = calloc(1, sizeof(Expr));
@@ -98,7 +97,7 @@ Expr* Factor() {
} }
Expr* Unary() { Expr* Unary() {
if (SMatch(2, Bang, Minus)) { if (Match(2, Bang, Minus)) {
Token* operator = Previous(); Token* operator = Previous();
Expr* right = Unary(); Expr* right = Unary();
Expr* expr = calloc(1, sizeof(Expr)); Expr* expr = calloc(1, sizeof(Expr));
@@ -115,8 +114,8 @@ Expr* Primary() {
Expr* expr = calloc(1, sizeof(Expr)); Expr* expr = calloc(1, sizeof(Expr));
expr->type = LITERAL; expr->type = LITERAL;
if (SMatch(3, FALSE, TRUE, NIL)) { if (Match(3, FALSE, TRUE, NIL)) {
expr->expression.Literal.type = SPeek();//CreateToken("false", FALSE); expr->expression.Literal.type = ParserPeek();//CreateToken("false", FALSE);
return expr; return expr;
} }
// if (SMatch(1, TRUE)) { // if (SMatch(1, TRUE)) {
@@ -128,12 +127,12 @@ Expr* Primary() {
// return expr; // return expr;
// } // }
if (SMatch(2, Number, String)) { if (Match(2, Number, String)) {
expr->expression.Literal.type = Previous(); expr->expression.Literal.type = Previous();
return expr; return expr;
} }
if (SMatch(1, LParen)) { if (Match(1, LParen)) {
free(expr); free(expr);
expr = Expression(); expr = Expression();
//Consume(RParen, "Expect ')' after expression."); //Consume(RParen, "Expect ')' after expression.");
@@ -144,13 +143,13 @@ Expr* Primary() {
return expr; return expr;
} }
int SMatch(int count, ...) { int Match(int count, ...) {
va_list list; va_list list;
va_start(list, count); va_start(list, count);
for(int i = 0; i < count; i++) { for(int i = 0; i < count; i++) {
if(Check(va_arg(list, TokenType))) { if(Check(va_arg(list, TokenType))) {
SAdvance(); AdvanceParser();
return 1; return 1;
} }
} }
@@ -159,15 +158,15 @@ int SMatch(int count, ...) {
} }
int Check(TokenType type) { int Check(TokenType type) {
if (SIsAtEnd()) return 0; if (ParserAtEnd()) return 0;
return SPeek()->type == type; return ParserPeek()->type == type;
} }
int SIsAtEnd() { int ParserAtEnd() {
return SPeek()->type == EndOF; return ParserPeek()->type == EndOF;
} }
Token* SPeek() { Token* ParserPeek() {
return ListOfTokens->tokens[Current]; return ListOfTokens->tokens[Current];
} }
@@ -175,17 +174,29 @@ Token* Previous() {
return ListOfTokens->tokens[Current - 1]; return ListOfTokens->tokens[Current - 1];
} }
Token* SAdvance() { Token* AdvanceParser() {
if (!SIsAtEnd()) Current++; if (!ParserAtEnd()) Current++;
return Previous(); return Previous();
} }
// Token* CreateToken(char* lexeme, TokenType type) { void PrintExpressionTree(const Expr* tree) {
// Token* token = calloc(1, sizeof(Token));
// token->type = type;
// token->lexeme = lexeme;
// token->length = strlen(lexeme);
// return token; }
// }
void FreeExpressionTree(Expr* tree) {
if (!tree) return;
if (tree->type == BINARY) {
FreeExpressionTree(tree->expression.Binary.left);
FreeExpressionTree(tree->expression.Binary.right);
//FreeToken(tree->expression.Binary.op);
}
else if (tree->type == UNARY) {
FreeExpressionTree(tree->expression.Unary.right);
//FreeToken(tree->expression.Unary.op);
}
//else if (tree->type == LITERAL) FreeToken(tree->expression.Literal.type);
free(tree);
}
parser.h
+2
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@@ -9,5 +9,7 @@
#include <string.h> #include <string.h>
Expr* GenerateExpressionTree(const TokenList* list); Expr* GenerateExpressionTree(const TokenList* list);
void PrintExpressionTree(const Expr*);
void FreeExpressionTree(Expr*);
#endif #endif
scanner.c
+29 -33
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@@ -8,13 +8,13 @@ int current; //points to the character currently being considered.
int length; int length;
int line = 1; int line = 1;
const char* SAdvance(void); const char* AdvanceScanner(void);
int SIsAtEnd(void); int ScannerAtEnd(void);
void ScanToken(TokenList*); void ScanToken(TokenList*);
TokenList* CreateList(void); TokenList* CreateList(void);
int AddToTokenList(Token*, TokenList*); int AddToTokenList(Token*, TokenList*);
int SMatch(char); int ScannerMatch(char);
char SPeek(void); char ScannerPeek(void);
char PeekNext(void); char PeekNext(void);
void ParseString(TokenList *); void ParseString(TokenList *);
void ParseNumber(TokenList *); void ParseNumber(TokenList *);
@@ -32,7 +32,7 @@ TokenList* ScanTokens(const char* source) {
TokenList* tokens = CreateList(); TokenList* tokens = CreateList();
while(!SIsAtEnd()) { while(!ScannerAtEnd()) {
start = current; start = current;
ScanToken(tokens); ScanToken(tokens);
} }
@@ -68,11 +68,7 @@ void DestroyTokenList(TokenList* list) {
if (!list) return; if (!list) return;
for(int i = 0; i < list->size; i++) { for(int i = 0; i < list->size; i++) {
//Only free objects that required allocation, i.e. not in the TokenTypeMappings FreeToken(list->tokens[i]);
if (list->tokens[i]->type == String || list->tokens[i]->type == Number || list->tokens[i]->type == Identifier)
free((void *) list->tokens[i]->lexeme);
free(list->tokens[i]);
} }
free(list->tokens); free(list->tokens);
@@ -102,7 +98,7 @@ int AddToTokenList(Token* token, TokenList* list) {
} }
void ScanToken(TokenList* tokens) { void ScanToken(TokenList* tokens) {
const char* c = SAdvance(); const char* c = AdvanceScanner();
switch (*c) { switch (*c) {
case '(': case '(':
@@ -136,23 +132,23 @@ void ScanToken(TokenList* tokens) {
AddToTokenList(CreateToken(NULL, line, Star), tokens); AddToTokenList(CreateToken(NULL, line, Star), tokens);
break; break;
case '!': case '!':
if (SMatch('=')) AddToTokenList(CreateToken(NULL, line, Bang_Equal), tokens); if (ScannerMatch('=')) AddToTokenList(CreateToken(NULL, line, Bang_Equal), tokens);
else AddToTokenList(CreateToken(NULL, line, Bang), tokens); else AddToTokenList(CreateToken(NULL, line, Bang), tokens);
break; break;
case '=': case '=':
if (SMatch('=')) AddToTokenList(CreateToken(NULL, line, Equal_Equal), tokens); if (ScannerMatch('=')) AddToTokenList(CreateToken(NULL, line, Equal_Equal), tokens);
else AddToTokenList(CreateToken(NULL, line, Equal), tokens); else AddToTokenList(CreateToken(NULL, line, Equal), tokens);
break; break;
case '<': case '<':
if (SMatch('=')) AddToTokenList(CreateToken(NULL, line, Less_Equal), tokens); if (ScannerMatch('=')) AddToTokenList(CreateToken(NULL, line, Less_Equal), tokens);
else AddToTokenList(CreateToken(NULL, line, Less), tokens); else AddToTokenList(CreateToken(NULL, line, Less), tokens);
break; break;
case '>': case '>':
if (SMatch('=')) AddToTokenList(CreateToken(NULL, line, Greater_Equal), tokens); if (ScannerMatch('=')) AddToTokenList(CreateToken(NULL, line, Greater_Equal), tokens);
else AddToTokenList(CreateToken(NULL, line, Greater), tokens); else AddToTokenList(CreateToken(NULL, line, Greater), tokens);
break; break;
case '/': case '/':
if (SMatch('/')) while(SPeek() != '\n' && !SIsAtEnd()) { SAdvance(); } if (ScannerMatch('/')) while(ScannerPeek() != '\n' && !ScannerAtEnd()) { AdvanceScanner(); }
else AddToTokenList(CreateToken(NULL, line, Slash), tokens); else AddToTokenList(CreateToken(NULL, line, Slash), tokens);
break; break;
@@ -180,16 +176,16 @@ void ScanToken(TokenList* tokens) {
} }
} }
int SIsAtEnd() { int ScannerAtEnd() {
return current >= length; return current >= length;
} }
const char* SAdvance() { const char* AdvanceScanner() {
return &source_code[current++]; return &source_code[current++];
} }
int SMatch(char expected) { int ScannerMatch(char expected) {
if (SIsAtEnd()) return 0; if (ScannerAtEnd()) return 0;
if (source_code[current] != expected) return 0; if (source_code[current] != expected) return 0;
current++; current++;
@@ -197,8 +193,8 @@ int SMatch(char expected) {
return 1; return 1;
} }
char SPeek() { char ScannerPeek() {
if (SIsAtEnd()) return '\0'; if (ScannerAtEnd()) return '\0';
return source_code[current]; return source_code[current];
} }
@@ -206,12 +202,12 @@ char SPeek() {
void ParseString(TokenList *list) { void ParseString(TokenList *list) {
start = current; //The start is currently pointing to the first double quote so we need to move it start = current; //The start is currently pointing to the first double quote so we need to move it
//to the next (first character) of the string literal. //to the next (first character) of the string literal.
while(SPeek() != '"' && !SIsAtEnd()) { while(ScannerPeek() != '"' && !ScannerAtEnd()) {
if (SPeek() == '\n') line++; if (ScannerPeek() == '\n') line++;
SAdvance(); AdvanceScanner();
} }
if (SIsAtEnd()) { if (ScannerAtEnd()) {
fprintf(stderr, "Unterminated string.\n"); fprintf(stderr, "Unterminated string.\n");
return; return;
} }
@@ -227,16 +223,16 @@ void ParseString(TokenList *list) {
AddToTokenList(CreateToken(lexeme, line, String), list); AddToTokenList(CreateToken(lexeme, line, String), list);
SAdvance(); // The closing ". AdvanceScanner(); // The closing ".
} }
void ParseNumber(TokenList* list) { void ParseNumber(TokenList* list) {
while(isdigit(SPeek())) SAdvance(); while(isdigit(ScannerPeek())) AdvanceScanner();
if (SPeek() == '.' && isdigit(PeekNext())) { if (ScannerPeek() == '.' && isdigit(PeekNext())) {
SAdvance(); AdvanceScanner();
while(isdigit(SPeek())) SAdvance(); while(isdigit(ScannerPeek())) AdvanceScanner();
} }
char* lexeme = calloc(current - start + 2, sizeof(char)); char* lexeme = calloc(current - start + 2, sizeof(char));
@@ -258,12 +254,12 @@ char PeekNext() {
} }
void ParseIdentifier(TokenList * list) { void ParseIdentifier(TokenList * list) {
while(IsAlpha(SPeek())) SAdvance(); while(IsAlpha(ScannerPeek())) AdvanceScanner();
char* lexeme = calloc(current - start + 2, sizeof(char)); char* lexeme = calloc(current - start + 2, sizeof(char));
snprintf(lexeme, current - start + 1, "%s", &source_code[start]); snprintf(lexeme, current - start + 1, "%s", &source_code[start]);
printf("%s\n", lexeme);
KeyValuePair* result = Get(lexeme); KeyValuePair* result = Get(lexeme);
if (result) { if (result) {
token.c
+8
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@@ -48,4 +48,12 @@ const char* GetLexemeMapping(TokenType type) {
} }
return NULL; return NULL;
}
void FreeToken(Token* token) {
if (!token) return;
if (token->type == String || token->type == Number || token->type == Identifier) free((void *) token->lexeme);
free(token);
} }
token.h
+1
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@@ -50,5 +50,6 @@ extern KeyValuePair TokenTypeMappings[TOKENTYPE_MAPPINGS_COUNT];
//If the first parameter is NULL, the token creation will attempt to infer the lexeme from the TokenType. //If the first parameter is NULL, the token creation will attempt to infer the lexeme from the TokenType.
Token* CreateToken(const char*, int, TokenType); Token* CreateToken(const char*, int, TokenType);
void FreeToken(Token*);
#endif #endif