#include "lexer.h"
#include "runtime.h"
#include "parser.h"
#include <algorithm>
#include <memory>
#include <stdexcept>
#include <string>
#include <vector>
#define FILENAME "jinja-parser"
namespace jinja {
// Helper to check type without asserting (useful for logic)
template<typename T>
static bool is_type(const statement_ptr & ptr) {
return dynamic_cast<const T*>(ptr.get()) != nullptr;
}
class parser {
const std::vector<token> & tokens;
size_t current = 0;
std::string source; // for error reporting
public:
parser(const std::vector<token> & t, const std::string & src) : tokens(t), source(src) {}
program parse() {
statements body;
while (current < tokens.size()) {
body.push_back(parse_any());
}
return program(std::move(body));
}
// NOTE: start_pos is the token index, used for error reporting
template<typename T, typename... Args>
std::unique_ptr<T> mk_stmt(size_t start_pos, Args&&... args) {
auto ptr = std::make_unique<T>(std::forward<Args>(args)...);
assert(start_pos < tokens.size());
ptr->pos = tokens[start_pos].pos;
return ptr;
}
private:
const token & peek(size_t offset = 0) const {
if (current + offset >= tokens.size()) {
static const token end_token{token::eof, "", 0};
return end_token;
}
return tokens[current + offset];
}
const token & next() {
if (current >= tokens.size()) {
throw parser_exception("Parser Error: Unexpected EOF", source, tokens.empty() ? 0 : tokens.back().pos);
}
return tokens[current++];
}
token expect(token::type type, const std::string& error) {
const auto & t = peek();
if (t.t != type) {
throw parser_exception("Parser Error: " + error + " (Got " + t.value + ")", source, t.pos);
}
current++;
return t;
}
void expect_identifier(const std::string & name) {
const auto & t = peek();
if (t.t != token::identifier || t.value != name) {
throw parser_exception("Expected identifier: " + name, source, t.pos);
}
current++;
}
bool is(token::type type) const {
return peek().t == type;
}
bool is_identifier(const std::string & name) const {
return peek().t == token::identifier && peek().value == name;
}
bool is_statement(const std::vector<std::string> & names) const {
if (peek(0).t != token::open_statement || peek(1).t != token::identifier) {
return false;
}
std::string val = peek(1).value;
return std::find(names.begin(), names.end(), val) != names.end();
}
statement_ptr parse_any() {
size_t start_pos = current;
switch (peek().t) {
case token::comment:
return mk_stmt<comment_statement>(start_pos, next().value);
case token::text:
return mk_stmt<string_literal>(start_pos, next().value);
case token::open_statement:
return parse_jinja_statement();
case token::open_expression:
return parse_jinja_expression();
default:
throw std::runtime_error("Unexpected token type");
}
}
statement_ptr parse_jinja_expression() {
// Consume {{ }} tokens
expect(token::open_expression, "Expected {{");
auto result = parse_expression();
expect(token::close_expression, "Expected }}");
return result;
}
statement_ptr parse_jinja_statement() {
// Consume {% token
expect(token::open_statement, "Expected {%");
if (peek().t != token::identifier) {
throw std::runtime_error("Unknown statement");
}
size_t start_pos = current;
std::string name = next().value;
statement_ptr result;
if (name == "set") {
result = parse_set_statement(start_pos);
} else if (name == "if") {
result = parse_if_statement(start_pos);
// expect {% endif %}
expect(token::open_statement, "Expected {%");
expect_identifier("endif");
expect(token::close_statement, "Expected %}");
} else if (name == "macro") {
result = parse_macro_statement(start_pos);
// expect {% endmacro %}
expect(token::open_statement, "Expected {%");
expect_identifier("endmacro");
expect(token::close_statement, "Expected %}");
} else if (name == "for") {
result = parse_for_statement(start_pos);
// expect {% endfor %}
expect(token::open_statement, "Expected {%");
expect_identifier("endfor");
expect(token::close_statement, "Expected %}");
} else if (name == "break") {
expect(token::close_statement, "Expected %}");
result = mk_stmt<break_statement>(start_pos);
} else if (name == "continue") {
expect(token::close_statement, "Expected %}");
result = mk_stmt<continue_statement>(start_pos);
} else if (name == "call") {
statements caller_args;
// bool has_caller_args = false;
if (is(token::open_paren)) {
// Optional caller arguments, e.g. {% call(user) dump_users(...) %}
caller_args = parse_args();
// has_caller_args = true;
}
auto callee = parse_primary_expression();
if (!is_type<identifier>(callee)) throw std::runtime_error("Expected identifier");
auto call_args = parse_args();
expect(token::close_statement, "Expected %}");
statements body;
while (!is_statement({"endcall"})) {
body.push_back(parse_any());
}
expect(token::open_statement, "Expected {%");
expect_identifier("endcall");
expect(token::close_statement, "Expected %}");
auto call_expr = mk_stmt<call_expression>(start_pos, std::move(callee), std::move(call_args));
result = mk_stmt<call_statement>(start_pos, std::move(call_expr), std::move(caller_args), std::move(body));
} else if (name == "filter") {
auto filter_node = parse_primary_expression();
if (is_type<identifier>(filter_node) && is(token::open_paren)) {
filter_node = parse_call_expression(std::move(filter_node));
}
expect(token::close_statement, "Expected %}");
statements body;
while (!is_statement({"endfilter"})) {
body.push_back(parse_any());
}
expect(token::open_statement, "Expected {%");
expect_identifier("endfilter");
expect(token::close_statement, "Expected %}");
result = mk_stmt<filter_statement>(start_pos, std::move(filter_node), std::move(body));
} else if (name == "generation" || name == "endgeneration") {
// Ignore generation blocks (transformers-specific)
// See https://github.com/huggingface/transformers/pull/30650 for more information.
result = mk_stmt<noop_statement>(start_pos);
++current;
} else {
throw std::runtime_error("Unknown statement: " + name);
}
return result;
}
statement_ptr parse_set_statement(size_t start_pos) {
// NOTE: `set` acts as both declaration statement and assignment expression
auto left = parse_expression_sequence();
statement_ptr value = nullptr;
statements body;
if (is(token::equals)) {
++current;
value = parse_expression_sequence();
} else {
// parsing multiline set here
expect(token::close_statement, "Expected %}");
while (!is_statement({"endset"})) {
body.push_back(parse_any());
}
expect(token::open_statement, "Expected {%");
expect_identifier("endset");
}
expect(token::close_statement, "Expected %}");
return mk_stmt<set_statement>(start_pos, std::move(left), std::move(value), std::move(body));
}
statement_ptr parse_if_statement(size_t start_pos) {
auto test = parse_expression();
expect(token::close_statement, "Expected %}");
statements body;
statements alternate;
// Keep parsing 'if' body until we reach the first {% elif %} or {% else %} or {% endif %}
while (!is_statement({"elif", "else", "endif"})) {
body.push_back(parse_any());
}
if (is_statement({"elif"})) {
size_t pos0 = current;
++current; // consume {%
++current; // consume 'elif'
alternate.push_back(parse_if_statement(pos0)); // nested If
} else if (is_statement({"else"})) {
++current; // consume {%
++current; // consume 'else'
expect(token::close_statement, "Expected %}");
// keep going until we hit {% endif %}
while (!is_statement({"endif"})) {
alternate.push_back(parse_any());
}
}
return mk_stmt<if_statement>(start_pos, std::move(test), std::move(body), std::move(alternate));
}
statement_ptr parse_macro_statement(size_t start_pos) {
auto name = parse_primary_expression();
auto args = parse_args();
expect(token::close_statement, "Expected %}");
statements body;
// Keep going until we hit {% endmacro
while (!is_statement({"endmacro"})) {
body.push_back(parse_any());
}
return mk_stmt<macro_statement>(start_pos, std::move(name), std::move(args), std::move(body));
}
statement_ptr parse_expression_sequence(bool primary = false) {
size_t start_pos = current;
statements exprs;
exprs.push_back(primary ? parse_primary_expression() : parse_expression());
bool is_tuple = is(token::comma);
while (is(token::comma)) {
++current; // consume comma
exprs.push_back(primary ? parse_primary_expression() : parse_expression());
}
return is_tuple ? mk_stmt<tuple_literal>(start_pos, std::move(exprs)) : std::move(exprs[0]);
}
statement_ptr parse_for_statement(size_t start_pos) {
// e.g., `message` in `for message in messages`
auto loop_var = parse_expression_sequence(true); // should be an identifier/tuple
if (!is_identifier("in")) throw std::runtime_error("Expected 'in'");
++current; // consume 'in'
// `messages` in `for message in messages`
auto iterable = parse_expression();
expect(token::close_statement, "Expected %}");
statements body;
statements alternate;
// Keep going until we hit {% endfor or {% else
while (!is_statement({"endfor", "else"})) {
body.push_back(parse_any());
}
if (is_statement({"else"})) {
++current; // consume {%
++current; // consume 'else'
expect(token::close_statement, "Expected %}");
while (!is_statement({"endfor"})) {
alternate.push_back(parse_any());
}
}
return mk_stmt<for_statement>(
start_pos,
std::move(loop_var), std::move(iterable),
std::move(body), std::move(alternate));
}
statement_ptr parse_expression() {
// Choose parse function with lowest precedence
return parse_if_expression();
}
statement_ptr parse_if_expression() {
auto a = parse_logical_or_expression();
if (is_identifier("if")) {
// Ternary expression
size_t start_pos = current;
++current; // consume 'if'
auto test = parse_logical_or_expression();
if (is_identifier("else")) {
// Ternary expression with else
size_t pos0 = current;
++current; // consume 'else'
auto false_expr = parse_if_expression(); // recurse to support chained ternaries
return mk_stmt<ternary_expression>(pos0, std::move(test), std::move(a), std::move(false_expr));
} else {
// Select expression on iterable
return mk_stmt<select_expression>(start_pos, std::move(a), std::move(test));
}
}
return a;
}
statement_ptr parse_logical_or_expression() {
auto left = parse_logical_and_expression();
while (is_identifier("or")) {
size_t start_pos = current;
token op = next();
left = mk_stmt<binary_expression>(start_pos, op, std::move(left), parse_logical_and_expression());
}
return left;
}
statement_ptr parse_logical_and_expression() {
auto left = parse_logical_negation_expression();
while (is_identifier("and")) {
size_t start_pos = current;
auto op = next();
left = mk_stmt<binary_expression>(start_pos, op, std::move(left), parse_logical_negation_expression());
}
return left;
}
statement_ptr parse_logical_negation_expression() {
// Try parse unary operators
if (is_identifier("not")) {
size_t start_pos = current;
auto op = next();
return mk_stmt<unary_expression>(start_pos, op, parse_logical_negation_expression());
}
return parse_comparison_expression();
}
statement_ptr parse_comparison_expression() {
// NOTE: membership has same precedence as comparison
// e.g., ('a' in 'apple' == 'b' in 'banana') evaluates as ('a' in ('apple' == ('b' in 'banana')))
auto left = parse_additive_expression();
while (true) {
token op;
size_t start_pos = current;
if (is_identifier("not") && peek(1).t == token::identifier && peek(1).value == "in") {
op = {token::identifier, "not in", tokens[current].pos};
++current; // consume 'not'
++current; // consume 'in'
} else if (is_identifier("in")) {
op = next();
} else if (is(token::comparison_binary_operator)) {
op = next();
} else break;
left = mk_stmt<binary_expression>(start_pos, op, std::move(left), parse_additive_expression());
}
return left;
}
statement_ptr parse_additive_expression() {
auto left = parse_multiplicative_expression();
while (is(token::additive_binary_operator)) {
size_t start_pos = current;
auto op = next();
left = mk_stmt<binary_expression>(start_pos, op, std::move(left), parse_multiplicative_expression());
}
return left;
}
statement_ptr parse_multiplicative_expression() {
auto left = parse_test_expression();
while (is(token::multiplicative_binary_operator)) {
size_t start_pos = current;
auto op = next();
left = mk_stmt<binary_expression>(start_pos, op, std::move(left), parse_test_expression());
}
return left;
}
statement_ptr parse_test_expression() {
auto operand = parse_filter_expression();
while (is_identifier("is")) {
size_t start_pos = current;
++current; // consume 'is'
bool negate = false;
if (is_identifier("not")) { ++current; negate = true; }
auto test_id = parse_primary_expression();
// FIXME: tests can also be expressed like this: if x is eq 3
if (is(token::open_paren)) test_id = parse_call_expression(std::move(test_id));
operand = mk_stmt<test_expression>(start_pos, std::move(operand), negate, std::move(test_id));
}
return operand;
}
statement_ptr parse_filter_expression() {
auto operand = parse_call_member_expression();
while (is(token::pipe)) {
size_t start_pos = current;
++current; // consume pipe
auto filter = parse_primary_expression();
if (is(token::open_paren)) filter = parse_call_expression(std::move(filter));
operand = mk_stmt<filter_expression>(start_pos, std::move(operand), std::move(filter));
}
return operand;
}
statement_ptr parse_call_member_expression() {
// Handle member expressions recursively
auto member = parse_member_expression(parse_primary_expression());
return is(token::open_paren)
? parse_call_expression(std::move(member)) // foo.x()
: std::move(member);
}
statement_ptr parse_call_expression(statement_ptr callee) {
size_t start_pos = current;
auto expr = mk_stmt<call_expression>(start_pos, std::move(callee), parse_args());
auto member = parse_member_expression(std::move(expr)); // foo.x().y
return is(token::open_paren)
? parse_call_expression(std::move(member)) // foo.x()()
: std::move(member);
}
statements parse_args() {
// comma-separated arguments list
expect(token::open_paren, "Expected (");
statements args;
while (!is(token::close_paren)) {
statement_ptr arg;
// unpacking: *expr
if (peek().t == token::multiplicative_binary_operator && peek().value == "*") {
size_t start_pos = current;
++current; // consume *
arg = mk_stmt<spread_expression>(start_pos, parse_expression());
} else {
arg = parse_expression();
if (is(token::equals)) {
// keyword argument
// e.g., func(x = 5, y = a or b)
size_t start_pos = current;
++current; // consume equals
arg = mk_stmt<keyword_argument_expression>(start_pos, std::move(arg), parse_expression());
}
}
args.push_back(std::move(arg));
if (is(token::comma)) {
++current; // consume comma
}
}
expect(token::close_paren, "Expected )");
return args;
}
statement_ptr parse_member_expression(statement_ptr object) {
size_t start_pos = current;
while (is(token::dot) || is(token::open_square_bracket)) {
auto op = next();
bool computed = op.t == token::open_square_bracket;
statement_ptr prop;
if (computed) {
prop = parse_member_expression_arguments();
expect(token::close_square_bracket, "Expected ]");
} else {
prop = parse_primary_expression();
}
object = mk_stmt<member_expression>(start_pos, std::move(object), std::move(prop), computed);
}
return object;
}
statement_ptr parse_member_expression_arguments() {
// NOTE: This also handles slice expressions colon-separated arguments list
// e.g., ['test'], [0], [:2], [1:], [1:2], [1:2:3]
statements slices;
bool is_slice = false;
size_t start_pos = current;
while (!is(token::close_square_bracket)) {
if (is(token::colon)) {
// A case where a default is used
// e.g., [:2] will be parsed as [undefined, 2]
slices.push_back(nullptr);
++current; // consume colon
is_slice = true;
} else {
slices.push_back(parse_expression());
if (is(token::colon)) {
++current; // consume colon after expression, if it exists
is_slice = true;
}
}
}
if (is_slice) {
statement_ptr start = slices.size() > 0 ? std::move(slices[0]) : nullptr;
statement_ptr stop = slices.size() > 1 ? std::move(slices[1]) : nullptr;
statement_ptr step = slices.size() > 2 ? std::move(slices[2]) : nullptr;
return mk_stmt<slice_expression>(start_pos, std::move(start), std::move(stop), std::move(step));
}
if (slices.empty()) {
return mk_stmt<blank_expression>(start_pos);
}
return std::move(slices[0]);
}
statement_ptr parse_primary_expression() {
size_t start_pos = current;
auto t = next();
switch (t.t) {
case token::numeric_literal:
if (t.value.find('.') != std::string::npos) {
return mk_stmt<float_literal>(start_pos, std::stod(t.value));
} else {
return mk_stmt<integer_literal>(start_pos, std::stoll(t.value));
}
case token::string_literal: {
std::string val = t.value;
while (is(token::string_literal)) {
val += next().value;
}
return mk_stmt<string_literal>(start_pos, val);
}
case token::identifier:
return mk_stmt<identifier>(start_pos, t.value);
case token::open_paren: {
auto expr = parse_expression_sequence();
expect(token::close_paren, "Expected )");
return expr;
}
case token::open_square_bracket: {
statements vals;
while (!is(token::close_square_bracket)) {
vals.push_back(parse_expression());
if (is(token::comma)) ++current;
}
++current;
return mk_stmt<array_literal>(start_pos, std::move(vals));
}
case token::open_curly_bracket: {
std::vector<std::pair<statement_ptr, statement_ptr>> pairs;
while (!is(token::close_curly_bracket)) {
auto key = parse_expression();
expect(token::colon, "Expected :");
pairs.push_back({std::move(key), parse_expression()});
if (is(token::comma)) ++current;
}
++current;
return mk_stmt<object_literal>(start_pos, std::move(pairs));
}
default:
throw std::runtime_error("Unexpected token: " + t.value + " of type " + std::to_string(t.t));
}
}
};
program parse_from_tokens(const lexer_result & lexer_res) {
return parser(lexer_res.tokens, lexer_res.source).parse();
}
} // namespace jinja