337 lines
12 KiB
C++
337 lines
12 KiB
C++
#include "lexer.h"
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#include "runtime.h"
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#include <cctype>
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#include <functional>
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#include <map>
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#include <string>
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#include <vector>
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#define FILENAME "jinja-lexer"
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namespace jinja {
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static void string_lstrip(std::string & s, const char * chars) {
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size_t start = s.find_first_not_of(chars);
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if (start == std::string::npos) {
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s.clear();
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} else {
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s.erase(0, start);
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}
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}
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static void string_rstrip(std::string & s, const char * chars) {
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size_t end = s.find_last_not_of(chars);
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if (end == std::string::npos) {
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s.clear();
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} else {
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s.erase(end + 1);
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}
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}
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lexer_result lexer::tokenize(const std::string & source) {
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std::vector<token> tokens;
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// NOTE: do NOT transform the source string (i.e. preprocessing), as we need to keep
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// the original character positions for error reporting etc.
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std::string src = source;
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if (source.empty()) {
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return {tokens, src};
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}
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// Normalize \r\n or \r to \n
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for (std::string::size_type pos = 0; (pos = src.find("\r\n", pos)) != std::string::npos; ) {
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src.erase(pos, 1);
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++pos;
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}
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for (std::string::size_type pos = 0; (pos = src.find("\r", pos)) != std::string::npos; ) {
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src.replace(pos, 1, 1, '\n');
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++pos;
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}
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// In the default configuration:
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// - a single trailing newline is stripped if present
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// - other whitespace (spaces, tabs, newlines etc.) is returned unchanged
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if (source.back() == '\n') {
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src.pop_back();
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}
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size_t pos = 0;
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size_t start_pos = 0;
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size_t curly_bracket_depth = 0;
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using pred = std::function<bool(char)>;
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auto consume_while = [&](const pred & predicate) -> std::string {
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std::string str;
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while (predicate(src[pos])) {
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// check for escape char
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if (src[pos] == '\\') {
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// consume backslash
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++pos;
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// check for end of input
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if (pos >= src.size()) {
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throw lexer_exception("unexpected end of input after escape character", source, pos);
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}
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// add escaped char
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char escaped_char = src[pos++];
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if (escape_chars.find(escaped_char) == escape_chars.end()) {
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throw lexer_exception(std::string("unknown escape character \\") + escaped_char, source, pos);
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}
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char unescaped_char = escape_chars.at(escaped_char);
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str += unescaped_char;
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continue;
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}
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str += src[pos++];
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if (pos > src.size()) {
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throw lexer_exception("unexpected end of input during consume_while", source, pos);
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}
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}
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return str;
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};
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auto next_pos_is = [&](std::initializer_list<char> chars, size_t n = 1) -> bool {
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if (pos + n >= src.size()) return false;
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for (char c : chars) {
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if (src[pos + n] == c) return true;
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}
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return false;
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};
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// note: default config for chat template: lstrip_blocks = true, trim_blocks = true
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// text\n[space]{block} --> text\n{block}
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bool opt_lstrip_blocks = true;
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// {block}\n[space]text --> {block}[space]text
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bool opt_trim_blocks = true;
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// options set dynamically based on current/last block
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bool is_lstrip_block = false; // example: {%-
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bool is_rstrip_block = false; // example: -%}
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while (pos < src.size()) {
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start_pos = pos;
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// JJ_DEBUG("lexer main loop at pos %zu: '%s...'", pos, src.substr(pos, 10).c_str());
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// First, consume all text that is outside of a Jinja statement or expression
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token::type last_token_type = tokens.empty()
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? token::close_statement // initial state
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: tokens.back().t;
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if (last_token_type == token::close_statement ||
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last_token_type == token::close_expression ||
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last_token_type == token::comment) {
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bool last_block_can_rm_newline = false;
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is_rstrip_block = false;
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if (pos > 3) {
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char c0 = src[pos - 3];
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char c1 = src[pos - 2];
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char c2 = src[pos - 1];
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// strip if: -[%}#]}text
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is_rstrip_block = c0 == '-'
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&& (c1 == '%' || c1 == '}' || c1 == '#')
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&& c2 == '}';
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// match behavior of hf.js: exclude {{ and }} cases, regex: ([#%-]})
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last_block_can_rm_newline = (c1 == '#' || c1 == '%' || c1 == '-') && c2 == '}';
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}
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size_t start = pos;
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size_t end = start;
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while (pos < src.size() &&
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// Keep going until we hit the next Jinja statement or expression
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!(
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src[pos] == '{' &&
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next_pos_is( {'%', '{', '#'} )
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)) {
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end = ++pos;
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}
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// equivalent to hf.js code: template.replace(/^[ \t]*({[#%-])/gm, "$1");
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if (opt_lstrip_blocks && src[pos] == '{' && next_pos_is({'%', '#', '-'})) {
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size_t current = end;
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while (current > start) {
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char c = src[current - 1];
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if (current == 1) {
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end = 0; // Trim from the start of the string
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break;
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}
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if (c == '\n') {
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end = current; // Trim from the start of the line
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break;
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}
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if (!std::isspace(static_cast<unsigned char>(c))) {
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break; // Found non-whitespace before newline, keep
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}
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--current;
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}
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}
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std::string text = src.substr(start, end - start);
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// equivalent to hf.js code: template.replace(/([#%-]})\n/g, "$1");
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if (opt_trim_blocks && last_block_can_rm_newline) {
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if (!text.empty() && text.front() == '\n') {
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text.erase(text.begin());
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}
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}
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if (is_rstrip_block) {
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// example: {last_block}[space]text
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// doing lstrip on text, effectively rstrip the LAST block
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// JJ_DEBUG("RSTRIP block detected, current text: '%s'", text.c_str());
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string_lstrip(text, " \t\r\n");
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}
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is_lstrip_block = src[pos] == '{' && next_pos_is({'{', '%', '#'}) && next_pos_is({'-'}, 2);
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if (is_lstrip_block) {
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// example: text[space]{current_block}
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// doing rstrip on text, effectively lstrip the CURRENT block
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// JJ_DEBUG("LSTRIP block detected, current text: '%s'", text.c_str());
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string_rstrip(text, " \t\r\n");
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}
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if (!text.empty()) {
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// JJ_DEBUG("consumed text: '%s'", text.c_str());
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tokens.push_back({token::text, text, start_pos});
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continue;
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}
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}
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// Possibly consume a comment
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// TODO: handle lstrip/rstrip for comments? (not important for now)
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if (src[pos] == '{' && next_pos_is( {'#'} )) {
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start_pos = pos;
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pos += 2; // Skip the opening {#
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std::string comment;
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while (!(src[pos] == '#' && next_pos_is( {'}'} ))) {
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if (pos + 2 >= src.size()) {
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throw lexer_exception("missing end of comment tag", source, pos);
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}
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comment += src[pos++];
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}
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JJ_DEBUG("consumed comment: '%s'", comment.c_str());
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tokens.push_back({token::comment, comment, start_pos});
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pos += 2; // Skip the closing #}
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continue;
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}
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if (src[pos] == '-' && (
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last_token_type == token::open_expression ||
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last_token_type == token::open_statement)
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) {
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JJ_DEBUG("lexer main loop at pos %zu: '%s...'", pos, src.substr(pos, 10).c_str());
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pos++; // consume '-' in {%- or {{-
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if (pos >= src.size()) break;
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}
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// Consume (and ignore) all whitespace inside Jinja statements or expressions
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consume_while([](char c) { return std::isspace(static_cast<unsigned char>(c)); });
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if (pos >= src.size()) break;
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char ch = src[pos];
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bool is_closing_block = ch == '-' && next_pos_is( {'%', '}'} );
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// Check for unary operators
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if (!is_closing_block && (ch == '-' || ch == '+')) {
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start_pos = pos;
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token::type last_token_type = tokens.empty() ? token::eof : tokens.back().t;
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if (last_token_type == token::text || last_token_type == token::eof) {
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throw lexer_exception(std::string("unexpected character: ") + ch, source, pos);
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}
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switch (last_token_type) {
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case token::identifier:
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case token::numeric_literal:
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case token::string_literal:
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case token::close_paren:
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case token::close_square_bracket:
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// Part of a binary operator
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// a - 1, 1 - 1, true - 1, "apple" - 1, (1) - 1, a[1] - 1
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// Continue parsing normally
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break;
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default: {
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// Is part of a unary operator
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// (-1), [-1], (1 + -1), not -1, -apple
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++pos; // Consume the operator
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// Check for numbers following the unary operator
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std::string num = consume_while(is_integer);
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std::string value = std::string(1, ch) + num;
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token::type t = num.empty() ? token::unary_operator : token::numeric_literal;
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// JJ_DEBUG("consumed unary operator or numeric literal: '%s'", value.c_str());
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tokens.push_back({t, value, start_pos});
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continue;
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}
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}
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}
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// Try to match one of the tokens in the mapping table
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bool matched = false;
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for (const auto & [seq, typ] : ordered_mapping_table) {
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start_pos = pos;
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// Inside an object literal, don't treat "}}" as expression-end
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if (seq == "}}" && curly_bracket_depth > 0) {
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continue;
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}
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if (pos + seq.size() <= src.size() && src.substr(pos, seq.size()) == seq) {
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tokens.push_back({typ, seq, start_pos});
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if (typ == token::open_expression) {
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curly_bracket_depth = 0;
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} else if (typ == token::open_curly_bracket) {
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++curly_bracket_depth;
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} else if (typ == token::close_curly_bracket) {
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--curly_bracket_depth;
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}
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pos += seq.size();
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matched = true;
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break; // continue main loop
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}
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}
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if (matched) continue; // continue main loop
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// Strings
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if (ch == '\'' || ch == '"') {
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start_pos = pos;
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++pos; // Skip opening quote
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std::string str = consume_while([ch](char c) { return c != ch; });
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// JJ_DEBUG("consumed string literal: '%s'", str.c_str());
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tokens.push_back({token::string_literal, str, start_pos});
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++pos; // Skip closing quote
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continue;
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}
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// Numbers
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if (is_integer(ch)) {
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start_pos = pos;
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std::string num = consume_while(is_integer);
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if (pos < src.size() && src[pos] == '.' && pos + 1 < src.size() && is_integer(src[pos + 1])) {
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++pos; // Consume '.'
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std::string frac = consume_while(is_integer);
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num += "." + frac;
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}
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// JJ_DEBUG("consumed numeric literal: '%s'", num.c_str());
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tokens.push_back({token::numeric_literal, num, start_pos});
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continue;
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}
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// Identifiers
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if (is_word(ch)) {
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start_pos = pos;
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std::string word = consume_while(is_word);
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// JJ_DEBUG("consumed identifier: '%s'", word.c_str());
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tokens.push_back({token::identifier, word, start_pos});
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continue;
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}
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throw lexer_exception(std::string("unexpected character: ") + ch, source, pos);
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}
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return {std::move(tokens), src};
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}
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} // namespace jinja
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