334 lines
12 KiB
C++
334 lines
12 KiB
C++
/* file token.hpp
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*
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* author: Roland Conybeare, Jul 2024
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*/
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#pragma once
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#include "tokentype.hpp"
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#include "xo/indentlog/print/tag.hpp"
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#include <stdexcept>
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#include <string>
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#include <cstdint>
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namespace xo {
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namespace tok {
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namespace detail {
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/* compute a * b^p, p >= 0 */
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constexpr double
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pow_aux(double a, double b, int p) {
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while (p > 0) {
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if (p % 2 == 1) {
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/* a * b^p = a * b^(2q + 1) = a.b * 10^(2q) */
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a *= b;
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p -= 1;
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} else {
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/* a * b^p = a * b^(2q) = a * (b^2)^q */
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b = b * b;
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p /= 2;
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}
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}
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/* a * b^0 = a */
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return a;
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}
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constexpr double
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pow10(int p) {
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if (p >= 0)
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return pow_aux(1.0, 10.0, p);
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else
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return 1.0 / pow_aux(1.0, 10.0, -p);
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}
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}
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template <typename CharT>
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class token {
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public:
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token() = default;
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token(tokentype tk_type, const std::string & text = "")
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: tk_type_{tk_type}, text_{text} {}
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static token invalid() { return token(); }
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static token i64_token(const std::string & txt) {
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return token(tokentype::tk_i64, txt);
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}
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static token f64_token(const std::string & txt) {
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return token(tokentype::tk_f64, txt);
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}
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static token string_token(const std::string & txt) {
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return token(tokentype::tk_string, txt);
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}
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static token symbol_token(const std::string & txt) {
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return token(tokentype::tk_symbol, txt);
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}
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static token leftangle() { return token(tokentype::tk_leftangle); }
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static token rightangle() { return token(tokentype::tk_rightangle); }
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static token leftparen() { return token(tokentype::tk_leftparen); }
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static token rightparen() { return token(tokentype::tk_rightparen); }
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static token leftbracket() { return token(tokentype::tk_leftbracket); }
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static token rightbracket() { return token(tokentype::tk_rightbracket); }
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static token leftbrace() { return token(tokentype::tk_leftbrace); }
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static token rightbrace() { return token(tokentype::tk_rightbrace); }
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static token dot() { return token(tokentype::tk_dot); }
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static token comma() { return token(tokentype::tk_comma); }
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static token colon() { return token(tokentype::tk_colon); }
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static token doublecolon() { return token(tokentype::tk_doublecolon); }
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static token semicolon() { return token(tokentype::tk_semicolon); }
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static token singleassign() { return token(tokentype::tk_singleassign); }
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static token assign() { return token(tokentype::tk_assign); }
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static token yields() { return token(tokentype::tk_yields); }
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static token type() { return token(tokentype::tk_type); }
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static token def() { return token(tokentype::tk_def); }
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static token lambda() { return token(tokentype::tk_lambda); }
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static token if_token() { return token(tokentype::tk_if); }
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static token let() { return token(tokentype::tk_let); }
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static token in() { return token(tokentype::tk_in); }
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tokentype tk_type() const { return tk_type_; }
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const std::string & text() const { return text_; }
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bool is_valid() const { return tk_type_ != tokentype::tk_invalid; }
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bool is_invalid() const { return tk_type_ == tokentype::tk_invalid; }
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/** expect input matching
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* [+|-][0-9][0-9]*
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**/
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std::int64_t i64_value() const;
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/** expect input matching
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* [+|-][0-9]*[.][0-9]*[e|E][+|-][0-9]*
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**/
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double f64_value() const;
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private:
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/** category for this token **/
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tokentype tk_type_ = tokentype::tk_invalid;
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/** characters comprising this token.
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* only provided for certain token types:
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*
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* tk_i64
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* tk_f64
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* tk_string
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* tk_symbol
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**/
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std::string text_;
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}; /*token*/
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template <typename CharT>
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std::int64_t
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token<CharT>::i64_value() const {
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if (tk_type_ != tokentype::tk_i64) {
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throw (std::runtime_error
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(tostr("token::i64_value",
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": token with type tk found where tk_i64 expected",
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xtag("tk", tk_type_))));
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}
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if (text_.empty()) {
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throw (std::runtime_error
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(tostr("token::i64_value",
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": unexpected empty input string for tk_i64 token")));
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}
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int sign = 1;
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int value = 0;
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{
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auto ix = text_.begin();
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auto end_ix = text_.end();
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CharT ch = *ix;
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if (ch == '+') {
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++ix;
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} else if (ch == '-') {
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sign = -1;
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++ix;
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}
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if (ix == end_ix) {
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throw (std::runtime_error
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(tostr("token::i64_value",
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": input text found where at least one digit expected",
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xtag("text", text_))));
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}
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for (; ix != end_ix; ++ix) {
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CharT ch = *ix;
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if ((ch >= '0') && (ch <= '9')) {
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value *= 10;
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value += (ch - '0');
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} else {
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throw (std::runtime_error
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(tostr("token::i64_value",
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": unexpected char ch in integer token",
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xtag("ch", ch))));
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}
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}
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}
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return sign * value;
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} /*i64_value*/
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template <typename CharT>
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double
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token<CharT>::f64_value() const {
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if (tk_type_ != tokentype::tk_f64) {
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throw (std::runtime_error
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(tostr("token::f64_value",
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": token with type tk found where tk_f64 expected",
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xtag("tk", tk_type_))));
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}
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if (text_.empty()) {
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throw (std::runtime_error
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(tostr("token::f64_value",
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": unexpected empty input string for tk_f64 token")));
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}
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int sign = 1;
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/* integer representing denormalized unsigned mantissa
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* (mantissa scaled by smallest power of 10 sufficient to make
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* it an integer)
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*/
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std::int64_t mantissa = 0;
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/* counts #of digits to the right of decimal point '.' */
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int rh_digits = 0;
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/* sign of exponent */
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int exp_sign = 1;
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/* value of exponenct = integer to the right of 'e' or 'E' */
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int exponent = 0;
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/* floating-point value will represent
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* sign * mantissa * 10^(sign*exponent - rh_digits)
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*/
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{
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auto ix = text_.begin();
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auto end_ix = text_.end();
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CharT ch = *ix;
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if (ch == '+') {
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++ix;
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} else if (ch == '-') {
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sign = -1;
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++ix;
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}
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if (ix == end_ix) {
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throw (std::runtime_error
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(tostr("token::f64_value",
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": input text found where at least one digit expected",
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xtag("text", text_))));
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}
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/* true iff decimal point '.' present in mantissa */
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bool have_decimal_point = false;
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/* true iff exponent prefix 'e' or 'E' present */
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//bool have_exponent = false;
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/* counts number of digits in mantissa
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* (both before and after, but not including, any decimal point
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*/
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int m_digits = 0;
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/* digits to the left of decimal point */
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int lh_digits = 0;
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/* loop over mantissa digits */
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for (; ix != end_ix; ++ix) {
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CharT ch = *ix;
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if (ch == '.') {
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if (have_decimal_point) {
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throw (std::runtime_error
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(tostr("token::f64_value",
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": input text found where at most one decimal point expected",
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xtag("text", text_))));
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}
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have_decimal_point = true;
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lh_digits = m_digits;
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} else if ((ch >= '0') && (ch <= '9')) {
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mantissa *= 10;
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mantissa += (ch - '0');
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++m_digits;
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} else if (ch == 'e' || ch == 'E') {
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//have_exponent = true;
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break; // done with mantissa
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} else {
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throw (std::runtime_error
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(tostr("token::i64_value",
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": unexpected char ch in integer token",
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xtag("ch", ch))));
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}
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}
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if (have_decimal_point)
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rh_digits = m_digits - lh_digits;
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if (ix != end_ix) {
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/* continue to read exponent */
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/* skip e|E */
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++ix;
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if (ix == end_ix) {
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throw (std::runtime_error
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(tostr("token::f64_value",
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": on input text, expect at least one digit following exponent marker e|E",
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xtag("text", text_))));
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}
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CharT ch = *ix;
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if (ch == '+') {
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++ix; /*skip*/
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} else if (ch == '-') {
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exp_sign = -1;
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++ix;
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}
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for (; ix != end_ix; ++ix) {
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CharT ch = *ix;
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if ((ch >= '0') && (ch <= '9')) {
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exponent *= 10;
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exponent += (ch - '0');
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} else {
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throw (std::runtime_error
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(tostr("token::f64_value",
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"; on input text, expect only digits following"
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" (possibly signed) exponenct marker",
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xtag("text", text_))));
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}
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}
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}
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}
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/* floating-point value will represent
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* sign * mantissa * 10^(sign*exponent - rh_digits)
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*/
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double mantissa_f64 = sign * mantissa;
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#ifdef OBSOLETE_DEBUG
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std::cerr << xtag("text", text_)
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<< xtag("rh_digits", rh_digits)
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<< xtag("mantissa_f64", mantissa_f64)
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<< xtag("exp_sign", exp_sign)
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<< xtag("exponent", exponent)
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<< std::endl;
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#endif
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double retval = (mantissa_f64
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* detail::pow10((exp_sign * exponent)
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- rh_digits));
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return retval;
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} /*f64_value*/
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} /*Namespace tok*/
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} /*namespace xo*/
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/* end token.hpp */
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