text reader passes tests

src/spider/compiler/Compiler.cpp

@@ -3,12 +3,140 @@
 #include <spider/compiler/common.hpp>
 #include <spider/compiler/text/utf8.hpp>
 
-namespace spider {
+#include <spider/compiler/text/TextReader.hpp>
 
+using namespace spider;
 
+class TestRunner {
+private:
+    int totalTests = 0;
+    int passedTests = 0;
 
+public:
+    void assertCondition(bool condition, const std::string& testName) {
+        totalTests++;
+        if (condition) {
+            std::cout << "  [PASS] " << testName << "\n";
+            passedTests++;
+        } else {
+            std::cout << "  [FAIL] " << testName << "\n";
+        }
+    }
+
+    void printSummary() const {
+        std::cout << "\n========================================\n";
+        std::cout << "Test Results: " << passedTests << "/" << totalTests << " passed.\n";
+        std::cout << "========================================\n";
+    }
+};
+
+// ============================================================================
+// TEST SUITES FOR StringTextReader
+// ============================================================================
+
+void test_basic_reading(TestRunner& runner) {
+    std::cout << "\n--- Running: Basic Reading Tests ---\n";
+    std::cout.flush();
+
+    StringTextReader reader("hello");
+
+    runner.assertCondition(reader.current().has_value() && reader.current().value() == 'h', "Initial current character is 'h'");
+    runner.assertCondition(reader.peekChar(1).has_value() && reader.peekChar(1).value() == 'e', "Peek +1 char is 'e'");
+
+    auto next = reader.nextChar(1);
+    runner.assertCondition(next.has_value() && next.value() == 'e', "Advance to next char gives 'e'");
+    runner.assertCondition(reader.current().has_value() && reader.current().value() == 'e', "Current character is now 'e'");
 }
 
+void test_eat_operations(TestRunner& runner) {
+    std::cout << "\n--- Running: Eat Operations Tests ---\n";
+    std::cout.flush();
+
+    StringTextReader reader("constexpr int x = 42;");
+
+    runner.assertCondition(reader.eat("constexpr"), "Eat exact string match 'constexpr'");
+    runner.assertCondition(reader.eat(' '), "Eat single space character");
+    runner.assertCondition(reader.eat("int"), "Eat second string match 'int'");
+
+    runner.assertCondition(!reader.eat("float"), "Eat fails on mismatched string 'float'");
+    runner.assertCondition(reader.eat(' '), "Eat single space after failure");
+    runner.assertCondition(reader.eat('x'), "Eat character 'x'");
+}
+
+void test_push_pop_rollback(TestRunner& runner) {
+    std::cout << "\n--- Running: Push/Pop Rollback Tests ---\n";
+    std::cout.flush();
+
+    StringTextReader reader("function_name()");
+
+    auto savedPos = reader.push();
+    runner.assertCondition(reader.eat("function_"), "Incomplete parse attempt");
+
+    // Rollback
+    reader.pop(savedPos);
+    runner.assertCondition(reader.current().has_value() && reader.current().value() == 'f', "Rollback restores cursor to 'f'");
+    runner.assertCondition(reader.eat("function_name"), "Subsequent match succeeds after rollback");
+}
+
+void test_commit(TestRunner& runner) {
+    std::cout << "\n--- Running: Buffer Commit Tests ---\n";
+    std::cout.flush();
+
+    StringTextReader reader("line1\nline2");
+
+    reader.eat("line1\n");
+    reader.commit(); // Discard historical rollback buffer
+
+    runner.assertCondition(reader.current().has_value() && reader.current().value() == 'l', "Current char after commit is 'l'");
+    runner.assertCondition(reader.eat("line2"), "Reading continues normally after commit");
+}
+
+void test_string_mutations(TestRunner& runner) {
+    std::cout << "\n--- Running: String Mutation Tests (set/append) ---\n";
+    std::cout.flush();
+
+    StringTextReader reader("foo");
+    runner.assertCondition(reader.eat("foo"), "Read initial text 'foo'");
+
+    reader.set("reset_text");
+    runner.assertCondition(reader.eat("reset_text"), "Read completely new text after set()");
+}
+
+void test_eof_handling(TestRunner& runner) {
+    std::cout << "\n--- Running: EOF & Error State Tests ---\n";
+    std::cout.flush();
+
+    StringTextReader reader("a");
+
+    runner.assertCondition(static_cast<bool>(reader), "Reader is valid initially");
+    runner.assertCondition(!reader.isEOF(), "isEOF is false initially");
+
+    reader.eat('a');
+    std::cout << "Index: " << reader.push().index << std::endl;
+    std::cout << "Value: " << reader.current().value_or(0) << std::endl;
+    runner.assertCondition(!reader.current().has_value(), "current() returns empty optional at EOF");
+    runner.assertCondition(reader.isEOF(), "isEOF is true after consuming all input");
+    runner.assertCondition(!reader.hasError(), "hasError remains false on normal EOF");
+}
+
+// ============================================================================
+// MAIN DRIVER
+// ============================================================================
+
 int main() {
+    std::cout << "========================================\n";
+    std::cout << "   StringTextReader Unit Test Suite     \n";
+    std::cout << "========================================\n";
+
+    TestRunner runner;
+    test_basic_reading(runner);
+    test_eat_operations(runner);
+    test_push_pop_rollback(runner);
+    test_commit(runner);
+    test_string_mutations(runner);
+    test_eof_handling(runner);
+    runner.printSummary();
+
     return 0;
 }
+

src/spider/compiler/assembler/AsmEBNF.cpp

@@ -4,7 +4,7 @@ namespace spider::asm_ebnf {
 
     // Token Factory
 
-    TokenFactory tf;
+    //TokenFactory tf;
 
     // Char Functions
 
@@ -28,117 +28,190 @@ namespace spider::asm_ebnf {
         return ch != u32('"');
     }
 
-    // (* Characters & Basic Predicates *)
+    const Token* letter;
-    const Token* letter = tf.fn(isUTF8Alpha);
+    const Token* digit;
-    const Token* digit = tf.choice("0123456789");
+    const Token* alpha_num_char;
-    const Token* alpha_num_char = tf.choice({ letter, digit });
 
-    const Token* hex_digit = tf.choice("0123456789ABCDEFabcdef");
+    const Token* hex_digit;
-    const Token* octal_digit = tf.choice("01234567");
+    const Token* octal_digit;
-    const Token* binary_digit = tf.choice("01");
+    const Token* binary_digit;
 
-    const Token* ws_char = tf.fn(isWhithespaceCharNotCrLf);
+    const Token* ws_char;
-    const Token* ws_optional = tf.tag(tf.rep(ws_char), "whitespace", true);
+    const Token* ws_optional;
-    const Token* whitespace = tf.tag(tf.seq({ ws_char, tf.rep(ws_char) }), "whitespace", true);
+    const Token* whitespace;
-    const Token* newline = tf.choice({ tf["\r\n"], tf["\r"], tf["\n"] });
+    const Token* newline;
-    const Token* utf8_char = tf.fn(isUTF8CharNotCrLf);
+    const Token* utf8_char;
 
-    const Token* char_escape = tf.seq({ tf["\\"], utf8_char });
+    const Token* char_escape;
-    const Token* char_content = tf.choice({ char_escape, tf.fn(isUTF8CharLitCont) });
+    const Token* char_content;
-    const Token* char_lit = tf.seq({ tf["'"], char_content, tf["'"] });
+    const Token* char_lit;
 
-    const Token* string_char = tf.choice({ char_escape, tf.fn(isUTF8StringLitCont) });
+    const Token* string_char;
-    const Token* string_lit = tf.seq({ tf["\""], tf.rep(string_char), tf["\""] });
+    const Token* string_lit;
 
-    // (* Literals *)
+    const Token* identifier;
-    const Token* identifier = tf.tag(tf.seq({
+    const Token* comment;
-        tf.choice({ letter, tf["_"] }),
-        tf.rep(tf.choice({ alpha_num_char, tf["_"] }))
-    }), "identifier", true);
 
-    const Token* comment = tf.tag(tf.seq({ tf[";"], tf.rep(utf8_char) }), "comment", true);
+    const Token* sign;
+    const Token* exponent_marker;
+    const Token* exponent;
 
-    const Token* sign = tf.choice("+-");
+    const Token* decimal_lit;
-    const Token* exponent_marker = tf.choice("eE");
+    const Token* float_lit;
-    const Token* exponent = tf.seq({ exponent_marker, tf.opt(sign), digit, tf.rep(digit) });
 
-    const Token* decimal_lit = tf.tag(tf.seq({
+    const Token* hex_lit;
-        tf.opt(sign),
+    const Token* octal_lit;
-        digit,
+    const Token* binary_lit;
-        tf.rep(digit),
-        tf.opt(tf.choice("BSIL"))
-    }), "decimal_lit", true);
 
-    const Token* float_lit = tf.tag(tf.seq({
+    const Token* literal;
-        tf.opt(sign),
+    const Token* literal_cast;
-        tf.choice({
+    const Token* literal_decl;
-            tf.seq({ digit, tf.rep(digit), tf["."], digit, tf.rep(digit), tf.opt(exponent) }),
-            tf.seq({ tf["."], digit, tf.rep(digit), tf.opt(exponent) }),
-            tf.seq({ digit, tf.rep(digit), exponent })
-        }),
-        tf.opt(tf.choice("FD"))
-    }), "float_lit", true);
 
-    const Token* hex_lit = tf.tag(tf.seq({ tf.opt(sign), tf["0x"], hex_digit, tf.rep(hex_digit) }), "hex_lit", true);
+    const Token* register_tok;
-    const Token* octal_lit = tf.tag(tf.seq({ tf.opt(sign), tf["0c"], octal_digit, tf.rep(octal_digit) }), "octal_lit", true);
-    const Token* binary_lit = tf.tag(tf.seq({ tf.opt(sign), tf["0b"], binary_digit, tf.rep(binary_digit) }), "binary_lit", true);
 
-    const Token* literal = tf.tag(tf.choice({ float_lit, decimal_lit, hex_lit, octal_lit, binary_lit, string_lit, char_lit }), "literal");
+    const Token* addrm_ind;
-    const Token* literal_cast = tf.tag(tf.seq({ tf.choice("BSILFD"), ws_optional, tf["("], ws_optional, literal, ws_optional, tf[")"] }), "literal_cast");
+    const Token* addrm_ptr;
-    const Token* literal_decl = tf.tag(tf.choice({ literal, literal_cast }), "literal_decl");
+    const Token* addrm_idx;
+    const Token* addrm_sca;
+    const Token* addrm_dis;
 
-    // (* Operands *)
+    const Token* addr_modes;
-    const Token* register_tok = tf.tag(tf.seq({ tf["R"], alpha_num_char }), "register", true);
+    const Token* operand;
 
-    const Token* addrm_ind = tf.tag(tf.seq({ tf["["], ws_optional, literal_decl, ws_optional, tf["]"] }), "addrm_ind", true);
+    const Token* opcode;
-    const Token* addrm_ptr = tf.tag(tf.seq({ tf["["], ws_optional, register_tok, ws_optional, tf["]"] }), "addrm_ptr", true);
+    const Token* operand_list;
+    const Token* instruction;
 
-    const Token* addrm_idx = tf.tag(tf.seq({
+    const Token* annotation_named;
-        tf["["], ws_optional, register_tok, ws_optional,
+    const Token* annotation_arg;
-        tf["+"], ws_optional, literal_decl, ws_optional, tf["]"]
+    const Token* annotation_args;
-    }), "addrm_idx", true);
+    const Token* annotation_pars;
+    const Token* annotation;
 
-    const Token* addrm_sca = tf.tag(tf.seq({
+    const Token* preprocessor_val;
-        tf["["], ws_optional, register_tok, ws_optional,
+    const Token* preprocessor;
-        tf["+"], ws_optional, register_tok, ws_optional,
-        tf["*"], ws_optional, literal_decl, ws_optional, tf["]"]
-    }), "addrm_sca", true);
 
-    const Token* addrm_dis = tf.tag(tf.seq({
+    const Token* label;
-        tf["["], ws_optional, register_tok, ws_optional,
+    const Token* line_label;
-        tf["+"], ws_optional, register_tok, ws_optional,
+    const Token* line_annotation;
-        tf["*"], ws_optional, literal_decl, ws_optional,
+    const Token* line_content;
-        tf["+"], ws_optional, literal_decl, ws_optional, tf["]"]
+    const Token* line;
-    }), "addrm_dis", true);
+    const Token* line_last;
+    const Token* program;
 
-    const Token* addr_modes = tf.tag(tf.choice({ addrm_dis, addrm_sca, addrm_idx, addrm_ptr, addrm_ind }), "addrm");
+    void initTokens(TokenFactory& tf) {
-    const Token* operand = tf.tag(tf.choice({ register_tok, identifier, literal_decl, addr_modes }), "operand");
+        // (* Characters & Basic Predicates *)
+        letter = tf.fn(isUTF8Alpha);
+        digit = tf.choice("0123456789");
+        alpha_num_char = tf.choice({ letter, digit });
 
-    // (* Generalized Instructions *)
+        hex_digit = tf.choice("0123456789ABCDEFabcdef");
+        octal_digit = tf.choice("01234567");
+        binary_digit = tf.choice("01");
 
-    const Token* opcode = tf.tag(tf.seq({ letter, tf.rep(alpha_num_char) }), "opcode", true);
+        ws_char = tf.fn(isWhithespaceCharNotCrLf);
-    const Token* operand_list = tf.seq({ operand, tf.rep(tf.seq({ tf[","], ws_optional, operand })) });
+        ws_optional = tf.tag(tf.rep(ws_char), "whitespace", true);
-    const Token* instruction = tf.tag(tf.seq({opcode, tf.opt(tf.seq({ whitespace, operand_list })) }), "instruction");
+        whitespace = tf.tag(tf.seq({ ws_char, tf.rep(ws_char) }), "whitespace", true);
+        newline = tf.choice({ tf["\r\n"], tf["\r"], tf["\n"] });
+        utf8_char = tf.fn(isUTF8CharNotCrLf);
 
-    // (* Added Preprocessor, Annotation *)
+        char_escape = tf.seq({ tf["\\"], utf8_char });
+        char_content = tf.choice({ char_escape, tf.fn(isUTF8CharLitCont) });
+        char_lit = tf.seq({ tf["'"], char_content, tf["'"] });
 
-    const Token* annotation_named = tf.tag(tf.seq({ identifier, ws_optional, tf["="], ws_optional, literal_decl }), "annotation_arg_named");
+        string_char = tf.choice({ char_escape, tf.fn(isUTF8StringLitCont) });
-    const Token* annotation_arg = tf.tag(tf.choice({ annotation_named, literal_decl }), "annotation_arg");
+        string_lit = tf.seq({ tf["\""], tf.rep(string_char), tf["\""] });
-    const Token* annotation_args = tf.seq({ annotation_arg, tf.rep(tf.seq({ ws_optional, tf[","], ws_optional, annotation_arg })) });
-    const Token* annotation_pars = tf.seq({ tf["("], ws_optional, annotation_args, ws_optional, tf[")"] });
-    const Token* annotation = tf.tag(tf.seq({ tf["@"], identifier, tf.opt(annotation_pars) }), "annotation");
 
-    const Token* preprocessor_val = tf.choice({ identifier, literal_decl });
+        // (* Literals *)
-    const Token* preprocessor = tf.tag(tf.seq({ tf["#"], identifier, whitespace, preprocessor_val }), "preprocessor");
+        identifier = tf.tag(tf.seq({
+            tf.choice({ letter, tf["_"] }),
+            tf.rep(tf.choice({ alpha_num_char, tf["_"] }))
+        }), "identifier", true);
 
-    // (* Line Structure & Program *)
+        comment = tf.tag(tf.seq({ tf[";"], tf.rep(utf8_char) }), "comment", true);
 
-    const Token* label = tf.tag(tf.seq({ identifier, tf[":"] }), "label");
+        sign = tf.choice("+-");
-    const Token* line_label = tf.seq({ label, tf.opt(tf.seq({ whitespace, instruction })) });
+        exponent_marker = tf.choice("eE");
-    const Token* line_annotation = tf.seq({ annotation, tf.opt(tf.seq({ whitespace, instruction })) });
+        exponent = tf.seq({ exponent_marker, tf.opt(sign), digit, tf.rep(digit) });
-    const Token* line_content = tf.choice({ preprocessor, line_annotation, line_label, instruction });
+
-    const Token* line = tf.seq({ ws_optional, tf.opt(line_content), ws_optional, tf.opt(comment), newline });
+        decimal_lit = tf.tag(tf.seq({
-    const Token* line_last = tf.seq({ ws_optional, tf.opt(line_content), ws_optional, tf.opt(comment) });
+            tf.opt(sign),
-    const Token* program = tf.seq({ tf.rep(line), tf.opt(line_last) });
+            digit,
+            tf.rep(digit),
+            tf.opt(tf.choice("BSIL"))
+        }), "decimal_lit", true);
+
+        float_lit = tf.tag(tf.seq({
+            tf.opt(sign),
+            tf.choice({
+                tf.seq({ digit, tf.rep(digit), tf["."], digit, tf.rep(digit), tf.opt(exponent) }),
+                tf.seq({ tf["."], digit, tf.rep(digit), tf.opt(exponent) }),
+                tf.seq({ digit, tf.rep(digit), exponent })
+            }),
+            tf.opt(tf.choice("FD"))
+        }), "float_lit", true);
+
+        hex_lit = tf.tag(tf.seq({ tf.opt(sign), tf["0x"], hex_digit, tf.rep(hex_digit) }), "hex_lit", true);
+        octal_lit = tf.tag(tf.seq({ tf.opt(sign), tf["0c"], octal_digit, tf.rep(octal_digit) }), "octal_lit", true);
+        binary_lit = tf.tag(tf.seq({ tf.opt(sign), tf["0b"], binary_digit, tf.rep(binary_digit) }), "binary_lit", true);
+
+        literal = tf.tag(tf.choice({ float_lit, decimal_lit, hex_lit, octal_lit, binary_lit, string_lit, char_lit }), "literal");
+        literal_cast = tf.tag(tf.seq({ tf.choice("BSILFD"), ws_optional, tf["("], ws_optional, literal, ws_optional, tf[")"] }), "literal_cast");
+        literal_decl = tf.tag(tf.choice({ literal, literal_cast }), "literal_decl");
+
+        // (* Operands *)
+        register_tok = tf.tag(tf.seq({ tf["R"], alpha_num_char }), "register", true);
+
+        addrm_ind = tf.tag(tf.seq({ tf["["], ws_optional, literal_decl, ws_optional, tf["]"] }), "addrm_ind", true);
+        addrm_ptr = tf.tag(tf.seq({ tf["["], ws_optional, register_tok, ws_optional, tf["]"] }), "addrm_ptr", true);
+
+        addrm_idx = tf.tag(tf.seq({
+            tf["["], ws_optional, register_tok, ws_optional,
+            tf["+"], ws_optional, literal_decl, ws_optional, tf["]"]
+        }), "addrm_idx", true);
+
+        addrm_sca = tf.tag(tf.seq({
+            tf["["], ws_optional, register_tok, ws_optional,
+            tf["+"], ws_optional, register_tok, ws_optional,
+            tf["*"], ws_optional, literal_decl, ws_optional, tf["]"]
+        }), "addrm_sca", true);
+
+        addrm_dis = tf.tag(tf.seq({
+            tf["["], ws_optional, register_tok, ws_optional,
+            tf["+"], ws_optional, register_tok, ws_optional,
+            tf["*"], ws_optional, literal_decl, ws_optional,
+            tf["+"], ws_optional, literal_decl, ws_optional, tf["]"]
+        }), "addrm_dis", true);
+
+        addr_modes = tf.tag(tf.choice({ addrm_dis, addrm_sca, addrm_idx, addrm_ptr, addrm_ind }), "addrm");
+        operand = tf.tag(tf.choice({ register_tok, identifier, literal_decl, addr_modes }), "operand");
+
+        // (* Generalized Instructions *)
+
+        opcode = tf.tag(tf.seq({ letter, tf.rep(alpha_num_char) }), "opcode", true);
+        operand_list = tf.seq({ operand, tf.rep(tf.seq({ tf[","], ws_optional, operand })) });
+        instruction = tf.tag(tf.seq({ opcode, tf.opt(tf.seq({ whitespace, operand_list })) }), "instruction");
+
+        // (* Added Preprocessor, Annotation *)
+
+        annotation_named = tf.tag(tf.seq({ identifier, ws_optional, tf["="], ws_optional, literal_decl }), "annotation_arg_named");
+        annotation_arg = tf.tag(tf.choice({ annotation_named, literal_decl }), "annotation_arg");
+        annotation_args = tf.seq({ annotation_arg, tf.rep(tf.seq({ ws_optional, tf[","], ws_optional, annotation_arg })) });
+        annotation_pars = tf.seq({ tf["("], ws_optional, annotation_args, ws_optional, tf[")"] });
+        annotation = tf.tag(tf.seq({ tf["@"], identifier, tf.opt(annotation_pars) }), "annotation");
+
+        preprocessor_val = tf.choice({ identifier, literal_decl });
+        preprocessor = tf.tag(tf.seq({ tf["#"], identifier, whitespace, preprocessor_val }), "preprocessor");
+
+        // (* Line Structure & Program *)
+
+        label = tf.tag(tf.seq({ identifier, tf[":"] }), "label");
+        line_label = tf.seq({ label, tf.opt(tf.seq({ whitespace, instruction })) });
+        line_annotation = tf.seq({ annotation, tf.opt(tf.seq({ whitespace, instruction })) });
+        line_content = tf.choice({ preprocessor, line_annotation, line_label, instruction });
+        line = tf.seq({ ws_optional, tf.opt(line_content), ws_optional, tf.opt(comment), newline });
+        line_last = tf.seq({ ws_optional, tf.opt(line_content), ws_optional, tf.opt(comment) });
+        program = tf.seq({ tf.rep(line), tf.opt(line_last) });
+    }
 
 }

src/spider/compiler/text/TextReader.cpp

@@ -8,11 +8,7 @@ namespace spider {
 
     // Text Reader //
 
-    TextReader::TextReader() : err(false), eof(false), bufferIndex(0) {
+    TextReader::TextReader() : err(false), eof(false), bufferIndex(0) {}
-        // Prime the buffer with the first character
-        // so current() is immediately valid
-        fillBufferTo(0);
-    }
 
     TextReader::~TextReader() {}
 
@@ -37,14 +33,25 @@ namespace spider {
     }
 
     bool TextReader::eat(const std::u32string& str) {
+        // case 0: no str
+        if(str.empty()) return true;
+
+        // prepare n chars
+        isize index_space = str.size() - 1;
+        fillBufferTo(index_space);
+
+        // fast reject
+        if(!hasBufferTo(index_space)) return false;
+
         // compare now
-        isize index;
+        for(isize i = 0; i <= index_space; i++) {
-        for(index = 0; index < str.size(); index++) {
+            if(str[i] != buffer[bufferIndex + i]) {
-            if(str[index] != peekChar(index)) return false;
+                return false;
+            }
         }
 
         // success!
-        nextChar(index);
+        consumeChars(str.size());
         return true;
     }
 
@@ -68,37 +75,30 @@ namespace spider {
         return char(ch);
     }
 
-    /**
-     * Returns the current character.
-     */
     optional<u32> TextReader::current() {
+        fillBufferTo(0);
         if (bufferIndex < buffer.size()) {
             return buffer[bufferIndex];
         }
         return {};
     }
 
-    /**
-     * Reads the next character and advances the position tracker.
-     */
     optional<u32> TextReader::nextChar(isize n) {
         // Ensure the character we are moving TO exists
-        if (fillBufferTo(n)) {
+        fillBufferTo(n); // index = n will be accessible
-            // advance n characters
+        // from [0, n] inclusive, equal to (n + 1) chars
-            while(n--) {
+
-                advance(buffer[bufferIndex]);
+        // remember partial success
-                bufferIndex++;
+        consumeChars(n); // n chars will be removed
-            }
+
-            return current();
+        // return current char
-        }
+        // current char, index = 0
-        return {};
+        return current();
     }
 
-    /**
-     * Keeps the next n-th character (n = 0 is current).
-     */
     optional<u32> TextReader::peekChar(isize n) {
-        if (fillBufferTo(n)) return buffer[bufferIndex + n];
+        fillBufferTo(n);
+        if (hasBufferTo(n)) return buffer[bufferIndex + n];
         return {};
     }
 
@@ -110,12 +110,16 @@ namespace spider {
         }
     }
 
-    isize TextReader::push() {
+    TextReader::State TextReader::push() {
-        return bufferIndex;
+        return { .err = err, .eof = eof, .at = at, .errmsg = errmsg, .index = bufferIndex };
     }
 
-    void TextReader::pop(isize index) {
+    void TextReader::pop(TextReader::State s) {
-        bufferIndex = std::min(index, bufferIndex);
+        err = s.err;
+        eof = s.eof;
+        at = s.at;
+        errmsg = s.errmsg;
+        bufferIndex = s.index;
     }
 
     /**
@@ -163,19 +167,27 @@ namespace spider {
         return true;
     }
 
-    /**
-     * Fills the buffer sequentially until it contains at least up
-     * to (bufferIndex + targetOffset).
-     */
     bool TextReader::fillBufferTo(isize targetOffset) {
-        isize targetSize = bufferIndex + targetOffset + 1;
+        isize targetSize = bufferIndex + targetOffset;
-        while (buffer.size() < targetSize) {
+        while (targetSize >= buffer.size()) {
             if(readChar()) continue;
             return false;
         }
         return true;
     }
 
+    bool TextReader::hasBufferTo(isize index) {
+        return bufferIndex + index < buffer.size();
+    }
+
+    void TextReader::consumeChars(isize n) {
+        // advance up to specified char.
+        for(isize i = 0; i < n && hasBufferTo(i); i++) {
+            advance(buffer[bufferIndex]);
+        }
+        bufferIndex += n;
+    }
+
     pos TextReader::getPosition() const {
         return at;
     }
@@ -212,24 +224,24 @@ namespace spider {
     // String Reader //
 
     StringTextReader::StringTextReader(std::string initialText)
-        : buffer(std::move(initialText)),
+        : txt_buffer(std::move(initialText)),
-        stringStream(std::make_unique<std::istringstream>(buffer)) {
+        stringStream(std::make_unique<std::istringstream>(txt_buffer)) { }
-    }
 
     std::istream& StringTextReader::getStream() {
         return *stringStream;
     }
 
     void StringTextReader::set(const std::string& newText) {
-        buffer = newText;
+        txt_buffer = newText;
-        stringStream = std::make_unique<std::istringstream>(buffer);
+        stringStream = std::make_unique<std::istringstream>(txt_buffer);
-    }
 
-    void StringTextReader::append(const std::string& extraText) {
+        buffer.clear();
-        std::streampos pos = stringStream->tellg();
+        txt_buffer.clear();
-        buffer += extraText;
+
-        stringStream = std::make_unique<std::istringstream>(buffer);
+        bufferIndex = 0;
-        stringStream->seekg(pos);
+        err = false;
+        eof = false;
+        at = pos();
     }
 
 }

src/spider/compiler/text/TextReader.hpp

@@ -34,11 +34,6 @@ namespace spider {
 
         std::string errmsg;
 
-        struct stored_char {
-            u8 byte_count;
-            u32 value;
-        };
-
         /**
          * Buffer of extracted characters.
          */
@@ -52,6 +47,16 @@ namespace spider {
          */
         isize bufferIndex;
 
+    public:
+
+        struct State {
+            bool err;
+            bool eof;
+            pos at;
+            std::string errmsg;
+            isize index;
+        };
+
     public:
 
         TextReader();
@@ -94,13 +99,16 @@ namespace spider {
         optional<u32> current();
 
         /**
-         * Reads the next n-th character.
+         * Skips n number of characters and returns
+         * the current one in that position.
          * n = 0 is a noop, since it's the current one.
+         * 
+         * Will advance until the EOF is reached.
          */
         optional<u32> nextChar(isize n = 1);
 
         /**
-         * Keeps the next n-th character
+         * Returns the n-th character following the current one.
          * n = 0 is the current one.
          */
         optional<u32> peekChar(isize n = 1);
@@ -121,14 +129,14 @@ namespace spider {
          * Inside a parser, this allows to roll
          * back the index to a specific position.
          */
-        isize push();
+        State push();
 
         /**
          * Sets the current buffer index.
          * Inside a parser, rolls back to
          * a previous position.
          */
-        void pop(isize index);
+        void pop(State s);
 
         /**
          * Returns true if the end of the stream has been reached.
@@ -160,8 +168,29 @@ namespace spider {
 
         virtual std::istream& getStream() = 0;
 
+        /**
+         * Fills the buffer sequentially until it the passed
+         * index can be safely accessed, relative to the current
+         * buffer position.
+         * 
+         * Returns false if that index could not be reached.
+         * Partial success is possible, check buffer.size()!
+         */
         bool fillBufferTo(isize index);
 
+        /**
+         * Verifies that the index can be safely accessed,
+         * relative to the current buffer position.
+         */
+        bool hasBufferTo(isize index);
+
+        /**
+         * Triggers the buffer to consume this number
+         * of characters from the buffer. This is a reverseable
+         * operation.
+         */
+        void consumeChars(isize n);
+
     };
 
     /**
@@ -188,7 +217,7 @@ namespace spider {
     class StringTextReader : public TextReader {
     private:
 
-        std::string buffer;
+        std::string txt_buffer;
         std::unique_ptr<std::istringstream> stringStream;
 
     public:
@@ -199,8 +228,6 @@ namespace spider {
 
         void set(const std::string& newText);
 
-        void append(const std::string& extraText);
-
     protected:
 
         std::istream& getStream() override;

src/spider/compiler/text/Token.cpp

@@ -9,9 +9,13 @@ namespace spider {
     // ============================================================================
 
     Token* TokenFactory::lit(std::string_view text) {
+        auto it = lit_cache.find(std::string(text));
+        if(it != lit_cache.end()) return it->second;
+
         auto p = std::make_unique<LitToken>(text);
         auto t = p.get();
-        lit_cache.emplace(text, std::move(p));
+        arena.emplace_back(std::move(p));
+        lit_cache.emplace(text, t);
         return t;
     }
 
@@ -63,7 +67,7 @@ namespace spider {
         return t;
     }
 
-    Token* TokenFactory::tag(const Token* target, std::string_view tagname, bool flatten = false) {
+    Token* TokenFactory::tag(const Token* target, std::string_view tagname, bool flatten) {
         uptr<Token> p = std::make_unique<TagToken>(target, tagname, flatten);
         auto t = p.get();
         arena.emplace_back(std::move(p));
@@ -111,12 +115,12 @@ namespace spider {
     // SeqToken Implementation
     // ============================================================================30520370
 
-    SeqToken::SeqToken(const vector<const Token*>& tokens) : tokens(tokens) {}
+    SeqToken::SeqToken(const vector<const Token*>& _tokens) : tokens(_tokens) {}
 
     TokenResult SeqToken::test(TextReader& ctx) const {
         // this is a common branch point
         TokenResult r;
-        isize i = ctx.push();
+        auto i = ctx.push();
 
         // All matching steps within a sequence must pass consecutively.
         for (const auto& token_ref : tokens) {
@@ -143,7 +147,7 @@ namespace spider {
     // OrToken Implementation
     // ============================================================================
 
-    OrToken::OrToken(const vector<const Token*>& tokens) : tokens(tokens) {}
+    OrToken::OrToken(const vector<const Token*>& _tokens) : tokens(_tokens) {}
 
     TokenResult OrToken::test(TextReader& ctx) const {
         // All matching steps within a sequence must pass consecutively.
@@ -195,7 +199,7 @@ namespace spider {
             TokenResult res = target->test(ctx);
             // Guard Clause: Break loop if sub-parser signals failure, or if an empty-matching
             // rule succeeded without advancing the buffer index (prevents dynamic parsing lockups).
-            if (!res.success || i == ctx.push()) {
+            if (!res.success || i.index == ctx.push().index) {
                 ctx.pop(i);
                 break;
             }

src/spider/compiler/text/Token.hpp

@@ -15,15 +15,15 @@ namespace spider {
         /** @brief Indicates if the token composition successfully matched the input boundary. */
         bool success = false;
 
-        optional<std::string_view> tag;
+        optional<std::string_view> tag = {};
 
         /**
          * @brief Holds the deep-copied UTF-32 matching substring upon victory.
          * @note Returns empty when success is false.
          */
-        std::u32string match;
+        std::u32string match = U"";
 
-        vector<TokenResult> child;
+        vector<TokenResult> child = {};
 
     };
 
@@ -61,7 +61,7 @@ namespace spider {
         std::vector<std::unique_ptr<Token>> arena;
 
         // Deduplication caches
-        std::unordered_map<std::string, const Token*> lit_cache;
+        std::unordered_map<std::string, Token*> lit_cache;
 
     public:
 
@@ -238,7 +238,7 @@ namespace spider {
 
     public:
 
-        TagToken(const Token* t, std::string_view tag, bool doflatten = false);
+        TagToken(const Token* t, std::string_view tag, bool doflatten);
 
         TokenResult test(TextReader& ctx) const override;