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104 lines
2.4 KiB
104 lines
2.4 KiB
// read_real().
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// This file contains a slimmed down version of read_complex().
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// It does not pull in all the complex function code.
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// General includes.
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#include "base/cl_sysdep.h"
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// Specification.
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#include "cln/real_io.h"
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// Implementation.
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#include "cln/io.h"
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#include "base/string/cl_spushstring.h"
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#include "cln/input.h"
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namespace cln {
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// We read an entire token (or even more, if it begins with #C) into a
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// buffer and then call read_real() on the buffer.
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class pushstring_hack : public cl_spushstring {
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public:
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char* start_pointer (void) { return buffer; }
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char* end_pointer (void) { return buffer+index; }
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};
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static bool number_char_p (char c)
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{
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if ((c >= '0') && (c <= '9'))
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return true;
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if (((c >= 'A') && (c <= 'Z')) || ((c >= 'a') && (c <= 'z')))
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return true;
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switch (c) {
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case '+': case '-': case '.': case '_': case '/':
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return true;
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default:
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return false;
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}
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}
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const cl_R read_real (std::istream& stream, const cl_read_flags& flags)
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{
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// One pre-allocated buffer. This reduces the allocation/free cost.
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static pushstring_hack buffer;
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var int c;
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// Skip whitespace at the beginning.
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loop {
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c = stream.get();
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if (stream.eof() || stream.fail()) goto eof;
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if ((c == ' ') || (c == '\t') || (c == '\n'))
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continue;
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else
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break;
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}
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// Found first non-whitespace character.
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// Numbers cannot cross lines. We can treat EOF and '\n' the same way.
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buffer.reset();
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if (c == '#') {
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if (!(flags.lsyntax & lsyntax_commonlisp))
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goto syntax1;
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buffer.push(c);
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// Read some digits, then a letter, then a token.
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loop {
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c = stream.get();
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if (stream.eof() || stream.fail()) goto eof;
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buffer.push(c);
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if ((c >= '0') && (c <= '9'))
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continue;
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else
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break;
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}
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if (!(((c >= 'A') && (c <= 'Z')) || ((c >= 'a') && (c <= 'z'))))
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goto syntax1;
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c = stream.get();
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if (stream.eof() || stream.fail()) goto eof;
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}
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// Read a number token.
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if (!number_char_p(c))
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goto syntax1;
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loop {
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buffer.push(c);
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c = stream.peek(); // Avoid fail state on EOF.
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if (stream.eof() || stream.fail() || !number_char_p(c))
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break;
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c = stream.get();
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}
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// Parse the number.
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return read_real(flags,
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buffer.start_pointer(), buffer.end_pointer(),
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NULL
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);
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// Handle syntax error.
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syntax1: buffer.push(c);
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throw read_number_bad_syntax_exception(buffer.start_pointer(),buffer.end_pointer());
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// Handle premature EOF.
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eof: throw read_number_eof_exception();
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}
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} // namespace cln
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