shithub: rgbds

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Refactor `readString`

Much more readable, and avoids `peek(nz)`

--- a/src/asm/lexer.c

+++ b/src/asm/lexer.c

@@ -692,6 +692,11 @@

 	free(expansion);

 }

+static bool isMacroChar(char c)

+{

+	return c == '@' || c == '#' || (c >= '0' && c <= '9');

+}

+

 static char const *readMacroArg(char name)

 {

 	char const *str;

@@ -795,7 +800,7 @@

 			/* If character is a backslash, check for a macro arg */

 			lexerState->macroArgScanDistance++;

 			c = peekInternal(distance + 1);

-			if (c == '@' || c == '#' || (c >= '0' && c <= '9')) {

+			if (isMacroChar(c)) {

 				char const *str = readMacroArg(c);

 				/*

@@ -1443,22 +1448,22 @@

 static void readString(void)

 {

-	size_t i = 0;

-

 	dbgPrint("Reading string\n");

 	lexerState->disableMacroArgs = true;

 	lexerState->disableInterpolation = true;

+	size_t i = 0;

 	bool multiline = false;

+	// We reach this function after reading a single quote, but we also support triple quotes

 	if (peek(0) == '"') {

 		shiftChars(1);

 		if (peek(0) == '"') {

-			/* """ begins a multi-line string */

+			// """ begins a multi-line string

 			shiftChars(1);

 			multiline = true;

 		} else {

-			/* "" is an empty string */

+			// "" is an empty string, skip the loop

 			goto finish;

 		}

 	}

@@ -1466,45 +1471,35 @@

 	for (;;) {

 		int c = peek(0);

-		if (c == '\r' || c == '\n') {

-			if (!multiline) {

-				/* '\r' or '\n' ends a single-line string early */

-				c = EOF;

-			} else if (c == '\r' && peek(1) == '\n') {

-				/* '\r\n' becomes '\n' in multi-line strings */

-				shiftChars(1);

-				c = '\n';

-			}

+		// '\r', '\n' or EOF ends a single-line string early

+		if (c == EOF || (!multiline && (c == '\r' || c == '\n'))) {

+			error("Unterminated string\n");

+			break;

 		}

+		// We'll be staying in the string, so we can safely consume the char

+		shiftChars(1);

+

+		// Handle CRLF (in multiline strings only, already handled above otherwise)

+		if (c == '\r' && peek(0) == '\n') {

+			shiftChars(1);

+			c = '\n';

+		}

+

 		switch (c) {

 		case '"':

 			if (multiline) {

-				/* """ ends a multi-line string */

-				if (peek(1) != '"' || peek(2) != '"')

+				// Only """ ends a multi-line string

+				if (peek(0) != '"' || peek(1) != '"')

 					break;

-				shiftChars(3);

-			} else {

-				shiftChars(1);

+				shiftChars(2);

 			}

-			if (i == sizeof(yylval.tzString)) {

-				i--;

-				warning(WARNING_LONG_STR, "String constant too long\n");

-			}

 			goto finish;

-		case EOF:

-			if (i == sizeof(yylval.tzString)) {

-				i--;

-				warning(WARNING_LONG_STR, "String constant too long\n");

-			}

-			error("Unterminated string\n");

-			goto finish;

-

-		case '\\': /* Character escape or macro arg */

-			c = peek(1);

+		case '\\': // Character escape or macro arg

+			c = peek(0);

 			switch (c) {

-			case '\\': /* Return that character unchanged */

+			case '\\': // Return that character unchanged

 			case '"':

 			case '{':

 			case '}':

@@ -1523,15 +1518,14 @@

 				shiftChars(1);

 				break;

-			/* Line continuation */

+			// Line continuation

 			case ' ':

 			case '\r':

 			case '\n':

-				shiftChars(1); /* Shift the backslash */

 				readLineContinuation();

 				continue;

-			/* Macro arg */

+			// Macro arg

 			case '@':

 			case '#':

 			case '0':

@@ -1544,13 +1538,13 @@

 			case '7':

 			case '8':

 			case '9':

-				shiftChars(2);

+				shiftChars(1);

 				char const *str = readMacroArg(c);

 				i = appendMacroArg(str, i);

-				continue; /* Do not copy an additional character */

+				continue; // Do not copy an additional character

-			case EOF: /* Can't really print that one */

+			case EOF: // Can't really print that one

 				error("Illegal character escape at end of input\n");

 				c = '\\';

 				break;

@@ -1561,8 +1555,9 @@

 			}

 			break;

-		case '{': /* Symbol interpolation */

-			shiftChars(1);

+		case '{': // Symbol interpolation

+			// We'll be exiting the string scope, so re-enable expansions

+			// (Not interpolations, since they're handled by the function itself...)

 			lexerState->disableMacroArgs = false;

 			char const *ptr = readInterpolation();

@@ -1570,16 +1565,20 @@

 				while (*ptr && i < sizeof(yylval.tzString))

 					yylval.tzString[i++] = *ptr++;

 			lexerState->disableMacroArgs = true;

-			continue; /* Do not copy an additional character */

+			continue; // Do not copy an additional character

-		/* Regular characters will just get copied */

+		// Regular characters will just get copied

 		}

-		if (i < sizeof(yylval.tzString)) /* Copy one extra to flag overflow */

+

+		if (i < sizeof(yylval.tzString)) // Copy one extra to flag overflow

 			yylval.tzString[i++] = c;

-		shiftChars(1);

 	}

 finish:

+	if (i == sizeof(yylval.tzString)) {

+		i--;

+		warning(WARNING_LONG_STR, "String constant too long\n");

+	}

 	yylval.tzString[i] = '\0';

 	dbgPrint("Read string \"%s\"\n", yylval.tzString);