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#include "module-text.h"
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
enum { CHUNK = 4096 };
/* state: pending continuation bytes (bits 0-1) and the allowed range of the
* next one (bits 2-4): 0 any, 1 A0-BF after E0, 2 80-9F after ED, 3 90-BF
* after F0, 4 80-8F after F4. */
bool pure_utf8_step(unsigned *state, PureSpan span) {
unsigned remaining = *state & 3, range = *state >> 2;
for (size_t i = 0; i < span.size; ++i) {
unsigned char b = span.data[i];
if (remaining) {
unsigned low = range == 1 ? 0xA0 : range == 3 ? 0x90 : 0x80;
unsigned high = range == 2 ? 0x9F : range == 4 ? 0x8F : 0xBF;
if (b < low || b > high) return false;
--remaining;
range = 0;
} else if (b < 0x80) {
continue;
} else if (b >= 0xC2 && b <= 0xDF) {
remaining = 1;
} else if (b >= 0xE0 && b <= 0xEF) {
remaining = 2;
range = b == 0xE0 ? 1 : b == 0xED ? 2 : 0;
} else if (b >= 0xF0 && b <= 0xF4) {
remaining = 3;
range = b == 0xF0 ? 3 : b == 0xF4 ? 4 : 0;
} else return false;
}
*state = remaining | range << 2;
return true;
}
bool pure_utf8_complete(unsigned state) { return (state & 3) == 0; }
bool pure_utf8_valid(PureSpan span) {
unsigned state = 0;
return pure_utf8_step(&state, span) && pure_utf8_complete(state);
}
size_t pure_utf8_scalars(PureSpan span) {
size_t count = 0;
for (size_t i = 0; i < span.size; ++i) count += (span.data[i] & 0xC0) != 0x80;
return count;
}
size_t pure_utf8_newlines(PureSpan span) {
size_t count = 0;
for (size_t i = 0; i < span.size; ++i) count += span.data[i] == '\n';
return count;
}
size_t pure_format_number(double value, char out[32]) {
if (value == 0) { memcpy(out, "0", 2); return 1; }
if (value == floor(value) && fabs(value) < 1e15) return (size_t)snprintf(out, 32, "%.0f", value);
for (int precision = 1; precision <= 17; ++precision) {
snprintf(out, 32, "%.*g", precision, value);
if (strtod(out, NULL) == value) break;
}
char *exponent = strchr(out, 'e');
if (exponent) {
char *digits = exponent + 2; /* after the sign */
while (digits[0] == '0' && digits[1]) memmove(digits, digits + 1, strlen(digits));
}
return strlen(out);
}
typedef struct { unsigned char *out; } Copy;
static bool copy(void *context, PureSpan span) {
Copy *c = context;
memcpy(c->out, span.data, span.size);
c->out += span.size;
return true;
}
static void read_bytes(const PureDraft *draft, PureVersion version, size_t offset, size_t length,
unsigned char *out) {
Copy c = {out};
if (length) pure_draft_read_version(draft, version, offset, length, copy, &c);
}
static size_t forward(const PureDraft *draft, PureVersion version, size_t position) {
if (position >= version.bytes) return version.bytes;
unsigned char lead;
read_bytes(draft, version, position, 1, &lead);
size_t length = lead < 0x80 ? 1 : lead < 0xE0 ? 2 : lead < 0xF0 ? 3 : 4;
return position + length <= version.bytes ? position + length : version.bytes;
}
static size_t backward(const PureDraft *draft, PureVersion version, size_t position) {
if (!position) return 0;
size_t take = position < 4 ? position : 4;
unsigned char bytes[4];
read_bytes(draft, version, position - take, take, bytes);
size_t at = take - 1;
while (at && (bytes[at] & 0xC0) == 0x80) --at;
return position - take + at;
}
/* Saturating: stops at the start or end, so work is bounded by the text size. */
size_t pure_text_step(const PureDraft *draft, PureVersion version, size_t position, double count) {
for (; count > 0 && position < version.bytes; --count) position = forward(draft, version, position);
for (; count < 0 && position > 0; ++count) position = backward(draft, version, position);
return position;
}
size_t pure_text_line_start(const PureDraft *draft, PureVersion version, size_t position) {
unsigned char chunk[CHUNK];
while (position) {
size_t take = position < CHUNK ? position : CHUNK;
read_bytes(draft, version, position - take, take, chunk);
for (size_t i = take; i-- > 0;)
if (chunk[i] == '\n') return position - take + i + 1;
position -= take;
}
return 0;
}
size_t pure_text_line_end(const PureDraft *draft, PureVersion version, size_t position) {
unsigned char chunk[CHUNK];
while (position < version.bytes) {
size_t take = version.bytes - position < CHUNK ? version.bytes - position : CHUNK;
read_bytes(draft, version, position, take, chunk);
for (size_t i = 0; i < take; ++i)
if (chunk[i] == '\n') return position + i;
position += take;
}
return version.bytes;
}
static size_t advance_within(const PureDraft *draft, PureVersion version, size_t position,
size_t columns, size_t limit) {
for (; columns && position < limit; --columns) position = forward(draft, version, position);
return position < limit ? position : limit;
}
/* Moves keep the column; with no further line the cursor goes to the end or
* the start of the text. */
size_t pure_text_line_step(const PureDraft *draft, PureVersion version, size_t position, double count) {
size_t start = pure_text_line_start(draft, version, position), column = 0;
for (size_t at = start; at < position; at = forward(draft, version, at)) ++column;
for (; count > 0; --count) {
size_t end = pure_text_line_end(draft, version, position);
if (end == version.bytes) return version.bytes;
size_t next = end + 1;
position = advance_within(draft, version, next, column, pure_text_line_end(draft, version, next));
}
for (; count < 0; ++count) {
size_t here = pure_text_line_start(draft, version, position);
if (!here) return 0;
size_t previous = pure_text_line_start(draft, version, here - 1);
position = advance_within(draft, version, previous, column, here - 1);
}
return position;
}
typedef struct { size_t count; unsigned unit; } Count;
static bool count_span(void *context, PureSpan span) {
Count *c = context;
c->count += c->unit ? pure_utf8_newlines(span) : pure_utf8_scalars(span);
return true;
}
size_t pure_text_count(const PureDraft *draft, PureVersion version, size_t position, unsigned unit) {
Count c = {0, unit};
if (position) pure_draft_read_version(draft, version, 0, position, count_span, &c);
return c.count + (unit ? 1 : 0);
}
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