1 files changed, 191 insertions, 0 deletions
diff --git a/src/parser.cc b/src/parser.cc
new file mode 100644
index 0000000..0f05790
--- /dev/null
+++ b/src/parser.cc
@@ -0,0 +1,191 @@
+#include "parser.h"
+#include "exceptions.h"
+
+#include <sstream>
+
+namespace SimpleParser {
+
+int8_t Parser::getPriority(char tmp)
+{
+	switch ( tmp ) {
+		case '-':
+			return 10;
+		case '+':
+			return 10;
+		case '/':
+			return 20;
+		case '*':
+			return 20;
+		case '^':
+			return 30;
+		case '(':
+			return 90;
+		case ')':
+			return 90;
+		case ',':
+			return -1;
+		default:
+			return -1;
+	}
+}
+
+std::vector<std::string> Parser::lexer(std::string term)
+{
+	std::string tmp;
+	std::string tmpNum;
+	std::string::iterator termIter;
+	std::vector<std::string> output;
+
+	int8_t   priority     = 0;
+	int8_t   lastPriority = 0;
+	uint32_t level        = 0;
+
+	for ( termIter = term.begin(); termIter != term.end(); termIter++ ) {
+		priority = this->getPriority(*termIter);
+
+		if ( priority == -1 || ( termIter == term.begin() && priority == 10 ) ) {
+			if ( level > 0 ) {
+				tmp += *termIter;
+			} else {
+				tmpNum += *termIter;
+			}
+		} else {
+			if ( lastPriority == -1 && level == 0 ) {
+				output.push_back(tmpNum);
+				tmpNum.clear();
+			}
+
+			switch ( *termIter ) {
+				case '(': {
+					if ( level > 0 ) {
+						tmp += *termIter;
+					}
+
+					level++;
+					break;
+				}
+				case ')': {
+					level--;
+
+					if ( level == 0 ) {
+						output.push_back(tmp);
+						tmp.clear();
+					}
+					else {
+						tmp += *termIter;
+					}
+					break;
+				}
+				default: {
+					if ( level == 0 ) {
+						std::string helper;
+						helper = *termIter;
+
+						output.push_back(helper);
+					}
+					else {
+						tmp += *termIter;
+					}
+					break;
+				}
+			}
+		}
+
+		lastPriority = priority;
+	}
+
+	if ( lastPriority == -1 ) {
+		output.push_back(tmpNum);
+	} else if ( lastPriority != 90 ) {
+		throw operator_exception();
+	}
+
+	if (level != 0) {
+		throw parenthese_exception();
+	}
+
+	if ( lastPriority == 90 && output.size() == 1 ) {
+		output = lexer(output[0]);
+	}
+
+	return output;
+}
+
+Node* Parser::buildTree(Tree *tree, std::string term) {
+	std::stack<Node*> operandStack;
+	std::stack<Node*> operatorStack;
+
+	std::vector<std::string> tmpLexer;
+	std::vector<std::string> lexerOutput = this->lexer(term);
+
+	int8_t priority;
+
+	for ( auto termIter = lexerOutput.begin(); termIter != lexerOutput.end(); termIter++ ) {
+		std::string& currTerm = (*termIter);
+		priority              = this->getPriority(currTerm[0]);
+
+		if ( priority != -1 && (*termIter).size() == 1 ) {
+			if ( !operatorStack.empty() ) {
+				OperatorNode *lastNode = static_cast<OperatorNode*>(operatorStack.top());
+
+				if ( this->getPriority(lastNode->getFunction()) < priority ) {
+					operatorStack.push( 
+						tree->addOperator(nullptr, currTerm[0])
+					);
+				} else {
+					Node *currOperator = operatorStack.top();
+					operatorStack.pop();
+
+					currOperator->rightChild = operandStack.top();
+					operandStack.pop();
+
+					currOperator->leftChild = operandStack.top();
+					operandStack.pop();
+
+					operandStack.push( currOperator );
+
+					termIter--;
+				}
+			} else {
+				operatorStack.push(tree->addOperator(nullptr, currTerm[0]));
+			}
+		} else {
+			tmpLexer = this->lexer(*termIter);
+
+			if ( tmpLexer.size() == 1 ) {
+				double value;
+				std::istringstream convertStream(tmpLexer[0]);
+				convertStream >> value;
+
+				operandStack.push(tree->addOperand(nullptr,value));
+			}
+			else if ( tmpLexer.size() > 1 ) {
+				operandStack.push(buildTree(tree, *termIter));
+			}
+		}
+	}
+
+	while ( !operatorStack.empty() ) {
+		OperatorNode *currOperator = static_cast<OperatorNode*>(operatorStack.top());
+		operatorStack.pop();
+
+		currOperator->rightChild = operandStack.top();
+		operandStack.pop();
+
+		currOperator->leftChild = operandStack.top();
+		operandStack.pop();
+
+		operandStack.push(currOperator);
+	}
+
+	return operandStack.top();
+}
+
+double Parser::calculate(std::string term) {
+	Tree termTree;
+	termTree.setRoot(this->buildTree(&termTree, term));
+
+	return termTree.solve();
+}
+
+}