Basic expression parsing

src/Expression.cpp

@@ -1,14 +1,95 @@
 #include "Expression.h"
 
-ExpressionInvalid Expression::Invalid = ExpressionInvalid();
+std::shared_ptr<Expression> Expression::Invalid = std::make_shared<Expression>(Expression::Kind::INVALID, Token::Invalid, nullptr, nullptr);
 
-std::string ExpressionInvalid::toString() {
-    return "Invalid";
+Expression::Expression(Kind kind, Token token, shared_ptr<Expression> left, shared_ptr<Expression> right) {
+    switch (kind) {
+        case LITERAL:
+            setupLiteral(token);
+            break;
+        case BINARY:
+            setupBinary(token, left, right);
+            break;
+        case INVALID:
+            break;
+    }
 }
 
-/*ExpressionInteger::ExpressionInteger(Token token) {
+void Expression::setupLiteral(Token token) {
+    bool isKindValid = token.isOneOf({Token::Kind::INTEGER});
+    if (!isKindValid)
+        return;
+
+    kind = LITERAL;
+    integer = stoi(token.getLexme());
 }
 
-std::string ExpressionInteger::toString() {
-    return "INTEGER";
-}*/
+void Expression::setupBinary(Token token, shared_ptr<Expression> left, shared_ptr<Expression> right) {
+    bool isKindValid = token.isOneOf({Token::Kind::PLUS, Token::Kind::MINUS, Token::Kind::STAR, Token::Kind::SLASH, Token::Kind::PERCENT});
+    bool isLeftValid = left != nullptr && left->getKind() != Kind::INVALID;
+    bool isRightValid = right != nullptr && right->getKind() != Kind::INVALID;
+
+    if (!isKindValid || !isLeftValid || !isRightValid)
+        return;
+
+    kind = BINARY;
+
+    switch (token.getKind()) {
+        case Token::Kind::PLUS:
+            operation = ADD;
+            break;
+        case Token::Kind::MINUS:
+            operation = SUB;
+            break;
+        case Token::Kind::STAR:
+            operation = MUL;
+            break;
+        case Token::Kind::SLASH:
+            operation = DIV;
+            break;
+        case Token::Kind::PERCENT:
+            operation = MOD;
+            break;
+        case Token::Kind::INVALID:
+            break;
+    }
+
+    this->left = left;
+    this->right = right;
+}
+
+Expression::Kind Expression::getKind() {
+    return kind;
+}
+
+bool Expression::operator==(Expression const& other) {
+    return kind == other.kind;
+}
+
+bool Expression::operator!=(Expression const& other) {
+    return kind != other.kind;
+}
+
+std::string Expression::toString() {
+    switch (kind) {
+        case LITERAL:
+            return to_string(integer);
+        case BINARY:
+            switch (operation) {
+                case ADD:
+                    return "<+ " + left->toString() + " " + right->toString() + ">";
+                case SUB:
+                    return "<- " + left->toString() + " " + right->toString() + ">";
+                case MUL:
+                    return "<* " + left->toString() + " " + right->toString() + ">";
+                case DIV:
+                    return "</ " + left->toString() + " " + right->toString() + ">";
+                case MOD:
+                    return "<% " + left->toString() + " " + right->toString() + ">";
+                case NONE:
+                    return "NONE";
+            }
+        case INVALID:
+            return "INVALID";
+    }
+}

src/Expression.h

@@ -3,23 +3,43 @@
 
 #include "Token.h"
 
-class ExpressionInvalid;
+using namespace std;
 
 class Expression {
 public:
-    static ExpressionInvalid Invalid;
+    enum Kind {
+        LITERAL,
+        BINARY,
+        INVALID
+    };
 
-    virtual std::string toString() = 0;
-};
+    enum Operation {
+        ADD,
+        SUB,
+        MUL,
+        DIV,
+        MOD,
+        NONE
+    };
 
-class ExpressionInvalid {
+private:
+    Kind kind = INVALID;
+    int64_t integer = 0;
+    Operation operation = NONE;
+    shared_ptr<Expression> left = nullptr;
+    shared_ptr<Expression> right = nullptr;
 
-};
+    void setupLiteral(Token token);
+    void setupBinary(Token token, shared_ptr<Expression> left, shared_ptr<Expression> right);
 
-/*class ExpressionInteger: Expression {
 public:
-    ExpressionInteger(Token token);
-    std::string toString() override;
-};*/
+    Expression(Kind kind, Token token, shared_ptr<Expression> left, shared_ptr<Expression> right);
+    Kind getKind();
+    bool operator==(Expression const& other);
+    bool operator!=(Expression const& other);
+    string toString();
+
+    static shared_ptr<Expression> Invalid;
+};
 
 #endif

src/Parser.cpp

@@ -1,24 +1,61 @@
 #include "Parser.h"
 
-Parser::Parser(std::vector<Token> tokens) : tokens(tokens) {
+Parser::Parser(vector<Token> tokens): tokens(tokens) {
 }
 
-/*Expression Parser::getExpression() {
+shared_ptr<Expression> Parser::getExpression() {
     return term();
-}*/
+}
 
-/*Expression Parser::term() {
+shared_ptr<Expression> Parser::term() {
+    shared_ptr<Expression> expression = factor();
 
-}*/
+    while (tokens.at(currentIndex).isOneOf({Token::Kind::PLUS, Token::Kind::MINUS})) {
+        expression = matchBinary(expression);
+    }
 
-/*Expression Parser::primary() {
+    return expression;
+}
 
-}*/
+shared_ptr<Expression> Parser::factor() {
+    shared_ptr<Expression> expression = primary();
 
-Expression Parser::matchInteger() {
-    //Token token = tokens.at(currentIndex);
-    //if (token.getKind() == Token::Kind::INTEGER)
-    //    ExpressionInteger(token);
+    while (tokens.at(currentIndex).isOneOf({Token::Kind::STAR, Token::Kind::SLASH, Token::Kind::PERCENT})) {
+        expression = matchBinary(expression);
+    }
+
+    return expression;
+}
+
+shared_ptr<Expression> Parser::primary() {
+    shared_ptr<Expression> expression = Expression::Invalid;
+
+    do {
+        if((expression = matchInteger()) != Expression::Invalid)
+            break;
+    
+    } while(false);
+
+    return expression;
+}
+
+shared_ptr<Expression> Parser::matchInteger() {
+    Token token = tokens.at(currentIndex);
+    if (token.getKind() == Token::Kind::INTEGER) {
+        currentIndex++;
+        return make_shared<Expression>(Expression::Kind::LITERAL, token, nullptr, nullptr);
+    }
+
+    return Expression::Invalid;
+}
+
+shared_ptr<Expression> Parser::matchBinary(shared_ptr<Expression> left) {
+    Token token = tokens.at(currentIndex);
+    if (token.isOneOf({Token::Kind::PLUS, Token::Kind::MINUS, Token::Kind::STAR, Token::Kind::SLASH, Token::Kind::PERCENT})) {
+        currentIndex++;
+        shared_ptr<Expression> right = factor();
+        return make_shared<Expression>(Expression::Kind::BINARY, token, left, right);
+    }
 
     return Expression::Invalid;
 }

src/Parser.h

@@ -5,19 +5,23 @@
 #include "Token.h"
 #include "Expression.h"
 
+using namespace std;
+
 class Parser {
 private:
-    std::vector<Token> tokens;
+    vector<Token> tokens;
     int currentIndex = 0;
 
-    //Expression term();
-    //Expression primary();
+    shared_ptr<Expression> term(); // +, -
+    shared_ptr<Expression> factor(); // *, /, %
+    shared_ptr<Expression> primary();
 
-    Expression matchInteger();
+    shared_ptr<Expression> matchInteger();
+    shared_ptr<Expression> matchBinary(shared_ptr<Expression> left);
 
 public:
-    Parser(std::vector<Token> tokens);
-    //Expression getExpression();
+    Parser(vector<Token> tokens);
+    shared_ptr<Expression> getExpression();
 };
 
 #endif

src/Token.cpp

@@ -21,6 +21,15 @@ bool Token::operator!=(Token const& other) {
     return kind != other.kind;
 }
 
+bool Token::isOneOf(std::vector<Kind> kinds) {
+    for (Kind &kind : kinds) {
+        if (kind == this->kind)
+            return true;
+    }
+        
+    return false;
+}
+
 std::string Token::toString() {
     switch (kind) {
         case PLUS:

src/Token.h

@@ -35,6 +35,7 @@ public:
     std::string getLexme();
     bool operator==(Token const& other);
     bool operator!=(Token const& other);
+    bool isOneOf(std::vector<Kind> kinds);
     std::string toString();
 
     static Token Invalid;

src/main.cpp

@@ -1,7 +1,13 @@
 #include <iostream>
 #include <fstream>
-#include "Lexer.h"
+
 #include "Token.h"
+#include "Lexer.h"
+
+#include "Expression.h"
+#include "Parser.h"
+
+using namespace std;
 
 std::string readFile(std::string fileName) {
     std::ifstream file(fileName.c_str(), std::ios::in | std::ios::binary | std::ios::ate);
@@ -30,5 +36,9 @@ int main(int argc, char **argv) {
         std::cout << token.toString() << " ";
     std::cout << std::endl;
 
+    Parser parser(tokens);
+    shared_ptr<Expression> expression = parser.getExpression();
+    cout << expression->toString() << endl;
+
     return 0;
 }