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#pragma once
namespace nall::Eval {
inline auto whitespace(char n) -> bool {
return n == ' ' || n == '\t' || n == '\r' || n == '\n';
}
//operator associativity and precedence:
// right: a[] a() a.b a++ a--
// left: &a *a !a ~a +a -a ++a --a
// left: a*b a/b a%b
// left: a+b a-b
// left: a<<<b a>>>b a<<b a>>b
// left: a&b
// left: a^b
// left: a|b
// left: a~b
// left: a<=b a>=b a<b a>b
// left: a==b a!=b
// left: a&&b
// left: a||b
// right: a??b a?b:c
// right: a=b a:=b a*=b a/=b a%=b a+=b a-=b a<<<=b a>>>=b a<<=b a>>=b a&=b a^=b a|=b a~=b
// left: a,b
//differences from C++17:
// a&b, a^b, a|b precedence was elevated above comparison operators
// a?b:c precedence was elevated above assignment operators
// a<<<b a>>>b a<<<=b a>>>=b rotation operators were added
// a~b a~=b concatenation operators were added
// a??b coalesce operator was added
inline auto parse(Node*& node, const char*& s, u32 depth) -> void {
auto unaryPrefix = [&](Node::Type type, u32 seek, u32 depth) {
auto parent = new Node(type);
parse(parent->link(0) = new Node, s += seek, depth);
node = parent;
};
auto unarySuffix = [&](Node::Type type, u32 seek, u32 depth) {
auto parent = new Node(type);
parent->link(0) = node;
parse(parent, s += seek, depth);
node = parent;
};
auto binary = [&](Node::Type type, u32 seek, u32 depth) {
auto parent = new Node(type);
parent->link(0) = node;
parse(parent->link(1) = new Node, s += seek, depth);
node = parent;
};
auto ternary = [&](Node::Type type, u32 seek, u32 depth) {
auto parent = new Node(type);
parent->link(0) = node;
parse(parent->link(1) = new Node, s += seek, depth);
if(s[0] != ':') throw "mismatched ternary";
parse(parent->link(2) = new Node, s += seek, depth);
node = parent;
};
auto separator = [&](Node::Type type, u32 seek, u32 depth) {
if(node->type != Node::Type::Separator) return binary(type, seek, depth);
u32 n = node->link.size();
parse(node->link(n) = new Node, s += seek, depth);
};
while(whitespace(s[0])) s++;
if(!s[0]) return;
if(s[0] == '(' && !node->link) {
parse(node, s += 1, 1);
if(*s++ != ')') throw "mismatched group";
}
if(isLiteral(s)) {
node->type = Node::Type::Literal;
node->literal = literal(s);
}
#define p() (!node->literal && !node->link)
while(true) {
while(whitespace(s[0])) s++;
if(!s[0]) return;
if(depth >= 17) break; //left associativity
if(s[0] == '(' && !p()) {
binary(Node::Type::Function, 1, 1);
if(*s++ != ')') throw "mismatched function";
continue;
}
if(s[0] == '[') {
binary(Node::Type::Subscript, 1, 1);
if(*s++ != ']') throw "mismatched subscript";
continue;
}
if(s[0] == '.') { binary(Node::Type::Member, 1, 17); continue; }
if(s[0] == '+' && s[1] == '+' && !p()) { unarySuffix(Node::Type::SuffixIncrement, 2, 17); continue; }
if(s[0] == '-' && s[1] == '-' && !p()) { unarySuffix(Node::Type::SuffixDecrement, 2, 17); continue; }
if(s[0] == '&' && p()) { unaryPrefix(Node::Type::Reference, 1, 16); continue; }
if(s[0] == '*' && p()) { unaryPrefix(Node::Type::Dereference, 1, 16); continue; }
if(s[0] == '!' && p()) { unaryPrefix(Node::Type::LogicalNot, 1, 16); continue; }
if(s[0] == '~' && p()) { unaryPrefix(Node::Type::BitwiseNot, 1, 16); continue; }
if(s[0] == '+' && s[1] != '+' && p()) { unaryPrefix(Node::Type::Positive, 1, 16); continue; }
if(s[0] == '-' && s[1] != '-' && p()) { unaryPrefix(Node::Type::Negative, 1, 16); continue; }
if(s[0] == '+' && s[1] == '+' && p()) { unaryPrefix(Node::Type::PrefixIncrement, 2, 16); continue; }
if(s[0] == '-' && s[1] == '-' && p()) { unaryPrefix(Node::Type::PrefixDecrement, 2, 16); continue; }
if(depth >= 16) break; //right associativity
if(depth >= 15) break; //left associativity
if(s[0] == '*' && s[1] != '=') { binary(Node::Type::Multiply, 1, 15); continue; }
if(s[0] == '/' && s[1] != '=') { binary(Node::Type::Divide, 1, 15); continue; }
if(s[0] == '%' && s[1] != '=') { binary(Node::Type::Modulo, 1, 15); continue; }
if(depth >= 14) break; //left associativity
if(s[0] == '+' && s[1] != '=') { binary(Node::Type::Add, 1, 14); continue; }
if(s[0] == '-' && s[1] != '=') { binary(Node::Type::Subtract, 1, 14); continue; }
if(depth >= 13) break; //left associativity
if(s[0] == '<' && s[1] == '<' && s[2] == '<' && s[3] != '=') { binary(Node::Type::RotateLeft, 3, 13); continue; }
if(s[0] == '>' && s[1] == '>' && s[2] == '>' && s[3] != '=') { binary(Node::Type::RotateRight, 3, 13); continue; }
if(s[0] == '<' && s[1] == '<' && s[2] != '=') { binary(Node::Type::ShiftLeft, 2, 13); continue; }
if(s[0] == '>' && s[1] == '>' && s[2] != '=') { binary(Node::Type::ShiftRight, 2, 13); continue; }
if(depth >= 12) break; //left associativity
if(s[0] == '&' && s[1] != '&' && s[1] != '=') { binary(Node::Type::BitwiseAnd, 1, 12); continue; }
if(depth >= 11) break; //left associativity
if(s[0] == '^' && s[1] != '^' && s[1] != '=') { binary(Node::Type::BitwiseXor, 1, 11); continue; }
if(depth >= 10) break; //left associativity
if(s[0] == '|' && s[1] != '|' && s[1] != '=') { binary(Node::Type::BitwiseOr, 1, 10); continue; }
if(depth >= 9) break; //left associativity
if(s[0] == '~' && s[1] != '=') { binary(Node::Type::Concatenate, 1, 9); continue; }
if(depth >= 8) break; //left associativity
if(s[0] == '<' && s[1] == '=') { binary(Node::Type::LessThanEqual, 2, 8); continue; }
if(s[0] == '>' && s[1] == '=') { binary(Node::Type::GreaterThanEqual, 2, 8); continue; }
if(s[0] == '<') { binary(Node::Type::LessThan, 1, 8); continue; }
if(s[0] == '>') { binary(Node::Type::GreaterThan, 1, 8); continue; }
if(depth >= 7) break; //left associativity
if(s[0] == '=' && s[1] == '=') { binary(Node::Type::Equal, 2, 7); continue; }
if(s[0] == '!' && s[1] == '=') { binary(Node::Type::NotEqual, 2, 7); continue; }
if(depth >= 6) break; //left associativity
if(s[0] == '&' && s[1] == '&') { binary(Node::Type::LogicalAnd, 2, 6); continue; }
if(depth >= 5) break; //left associativity
if(s[0] == '|' && s[1] == '|') { binary(Node::Type::LogicalOr, 2, 5); continue; }
if(s[0] == '?' && s[1] == '?') { binary(Node::Type::Coalesce, 2, 4); continue; }
if(s[0] == '?' && s[1] != '?') { ternary(Node::Type::Condition, 1, 4); continue; }
if(depth >= 4) break; //right associativity
if(s[0] == '=') { binary(Node::Type::Assign, 1, 3); continue; }
if(s[0] == ':' && s[1] == '=') { binary(Node::Type::Create, 2, 3); continue; }
if(s[0] == '*' && s[1] == '=') { binary(Node::Type::AssignMultiply, 2, 3); continue; }
if(s[0] == '/' && s[1] == '=') { binary(Node::Type::AssignDivide, 2, 3); continue; }
if(s[0] == '%' && s[1] == '=') { binary(Node::Type::AssignModulo, 2, 3); continue; }
if(s[0] == '+' && s[1] == '=') { binary(Node::Type::AssignAdd, 2, 3); continue; }
if(s[0] == '-' && s[1] == '=') { binary(Node::Type::AssignSubtract, 2, 3); continue; }
if(s[0] == '<' && s[1] == '<' && s[2] == '<' && s[3] == '=') { binary(Node::Type::AssignRotateLeft, 4, 3); continue; }
if(s[0] == '>' && s[1] == '>' && s[2] == '>' && s[3] == '=') { binary(Node::Type::AssignRotateRight, 4, 3); continue; }
if(s[0] == '<' && s[1] == '<' && s[2] == '=') { binary(Node::Type::AssignShiftLeft, 3, 3); continue; }
if(s[0] == '>' && s[1] == '>' && s[2] == '=') { binary(Node::Type::AssignShiftRight, 3, 3); continue; }
if(s[0] == '&' && s[1] == '=') { binary(Node::Type::AssignBitwiseAnd, 2, 3); continue; }
if(s[0] == '^' && s[1] == '=') { binary(Node::Type::AssignBitwiseXor, 2, 3); continue; }
if(s[0] == '|' && s[1] == '=') { binary(Node::Type::AssignBitwiseOr, 2, 3); continue; }
if(s[0] == '~' && s[1] == '=') { binary(Node::Type::AssignConcatenate, 2, 3); continue; }
if(depth >= 3) break; //right associativity
if(depth >= 2) break; //left associativity
if(s[0] == ',') { separator(Node::Type::Separator, 1, 2); continue; }
if(depth >= 1 && (s[0] == ')' || s[0] == ']')) break;
while(whitespace(s[0])) s++;
if(!s[0]) break;
throw "unrecognized terminal";
}
#undef p
}
inline auto parse(const string& expression) -> Node* {
auto result = new Node;
const char* p = expression;
parse(result, p, 0);
return result;
}
}
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