<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `src/parser.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>parser.rs - source</title><link rel="stylesheet" type="text/css" href="../../normalize.css"><link rel="stylesheet" type="text/css" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../../light.css" id="themeStyle"><link rel="stylesheet" type="text/css" href="../../dark.css" disabled ><link rel="stylesheet" type="text/css" href="../../ayu.css" disabled ><script id="default-settings"></script><script src="../../storage.js"></script><script src="../../crates.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="icon" type="image/svg+xml" href="../../favicon.svg">
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</pre><pre class="rust">
<span class="kw">use</span> <span class="kw">crate</span><span class="ident">::lexer</span>::{<span class="ident">Lexer</span>, <span class="ident">Token</span>};
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>, <span class="ident">PartialEq</span>)]</span>
<span class="kw">pub</span> <span class="kw">enum</span> <span class="ident">ExprAST</span> {
<span class="doccomment">/// Number - Expression class for numeric literals like "1.0".</span>
<span class="ident">Number</span>(<span class="ident">f64</span>),
<span class="doccomment">/// Variable - Expression class for referencing a variable, like "a".</span>
<span class="ident">Variable</span>(<span class="ident">String</span>),
<span class="doccomment">/// Binary - Expression class for a binary operator.</span>
<span class="ident">Binary</span>(<span class="ident">char</span>, <span class="ident">Box</span><span class="op"><</span><span class="ident">ExprAST</span><span class="op">></span>, <span class="ident">Box</span><span class="op"><</span><span class="ident">ExprAST</span><span class="op">></span>),
<span class="doccomment">/// Call - Expression class for function calls.</span>
<span class="ident">Call</span>(<span class="ident">String</span>, <span class="ident">Vec</span><span class="op"><</span><span class="ident">ExprAST</span><span class="op">></span>),
}
<span class="doccomment">/// PrototypeAST - This class represents the "prototype" for a function,</span>
<span class="doccomment">/// which captures its name, and its argument names (thus implicitly the number</span>
<span class="doccomment">/// of arguments the function takes).</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>, <span class="ident">PartialEq</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">PrototypeAST</span>(<span class="kw">pub</span> <span class="ident">String</span>, <span class="kw">pub</span> <span class="ident">Vec</span><span class="op"><</span><span class="ident">String</span><span class="op">></span>);
<span class="doccomment">/// FunctionAST - This class represents a function definition itself.</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>, <span class="ident">PartialEq</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">FunctionAST</span>(<span class="kw">pub</span> <span class="ident">PrototypeAST</span>, <span class="kw">pub</span> <span class="ident">ExprAST</span>);
<span class="doccomment">/// Parse result with String as Error type (to be compliant with tutorial).</span>
<span class="kw">type</span> <span class="ident">ParseResult</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="op">=</span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">T</span>, <span class="ident">String</span><span class="op">></span>;
<span class="doccomment">/// Parser for the `kaleidoscope` language.</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Parser</span><span class="op"><</span><span class="ident">I</span><span class="op">></span>
<span class="kw">where</span>
<span class="ident">I</span>: <span class="ident">Iterator</span><span class="op"><</span><span class="ident">Item</span> <span class="op">=</span> <span class="ident">char</span><span class="op">></span>,
{
<span class="ident">lexer</span>: <span class="ident">Lexer</span><span class="op"><</span><span class="ident">I</span><span class="op">></span>,
<span class="ident">cur_tok</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">Token</span><span class="op">></span>,
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span><span class="op">></span> <span class="ident">Parser</span><span class="op"><</span><span class="ident">I</span><span class="op">></span>
<span class="kw">where</span>
<span class="ident">I</span>: <span class="ident">Iterator</span><span class="op"><</span><span class="ident">Item</span> <span class="op">=</span> <span class="ident">char</span><span class="op">></span>,
{
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new</span>(<span class="ident">lexer</span>: <span class="ident">Lexer</span><span class="op"><</span><span class="ident">I</span><span class="op">></span>) <span class="op">-</span><span class="op">></span> <span class="self">Self</span> {
<span class="ident">Parser</span> {
<span class="ident">lexer</span>,
<span class="ident">cur_tok</span>: <span class="prelude-val">None</span>,
}
}
<span class="comment">// -----------------------</span>
<span class="comment">// Simple Token Buffer</span>
<span class="comment">// -----------------------</span>
<span class="doccomment">/// Implement the global variable `int CurTok;` from the tutorial.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Panics</span>
<span class="doccomment">/// Panics if the parser doesn't have a current token.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">cur_tok</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="kw-2">&</span><span class="ident">Token</span> {
<span class="self">self</span>.<span class="ident">cur_tok</span>.<span class="ident">as_ref</span>().<span class="ident">expect</span>(<span class="string">"Parser: Expected cur_token!"</span>)
}
<span class="doccomment">/// Advance the `cur_tok` by getting the next token from the lexer.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Implement the fucntion `int getNextToken();` from the tutorial.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">get_next_token</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) {
<span class="self">self</span>.<span class="ident">cur_tok</span> <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="self">self</span>.<span class="ident">lexer</span>.<span class="ident">gettok</span>());
}
<span class="comment">// ----------------------------</span>
<span class="comment">// Basic Expression Parsing</span>
<span class="comment">// ----------------------------</span>
<span class="doccomment">/// numberexpr ::= number</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Implement `std::unique_ptr<ExprAST> ParseNumberExpr();` from the tutorial.</span>
<span class="kw">fn</span> <span class="ident">parse_num_expr</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">ParseResult</span><span class="op"><</span><span class="ident">ExprAST</span><span class="op">></span> {
<span class="kw">match</span> <span class="kw-2">*</span><span class="self">self</span>.<span class="ident">cur_tok</span>() {
<span class="ident">Token::Number</span>(<span class="ident">num</span>) <span class="op">=</span><span class="op">></span> {
<span class="comment">// Consume the number token.</span>
<span class="self">self</span>.<span class="ident">get_next_token</span>();
<span class="prelude-val">Ok</span>(<span class="ident">ExprAST::Number</span>(<span class="ident">num</span>))
}
<span class="kw">_</span> <span class="op">=</span><span class="op">></span> <span class="macro">unreachable!</span>(),
}
}
<span class="doccomment">/// parenexpr ::= '(' expression ')'</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Implement `std::unique_ptr<ExprAST> ParseParenExpr();` from the tutorial.</span>
<span class="kw">fn</span> <span class="ident">parse_paren_expr</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">ParseResult</span><span class="op"><</span><span class="ident">ExprAST</span><span class="op">></span> {
<span class="comment">// Eat '(' token.</span>
<span class="macro">assert_eq!</span>(<span class="kw-2">*</span><span class="self">self</span>.<span class="ident">cur_tok</span>(), <span class="ident">Token::Char</span>(<span class="string">'('</span>));
<span class="self">self</span>.<span class="ident">get_next_token</span>();
<span class="kw">let</span> <span class="ident">v</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">parse_expression</span>()<span class="question-mark">?</span>;
<span class="kw">if</span> <span class="kw-2">*</span><span class="self">self</span>.<span class="ident">cur_tok</span>() <span class="op">=</span><span class="op">=</span> <span class="ident">Token::Char</span>(<span class="string">')'</span>) {
<span class="comment">// Eat ')' token.</span>
<span class="self">self</span>.<span class="ident">get_next_token</span>();
<span class="prelude-val">Ok</span>(<span class="ident">v</span>)
} <span class="kw">else</span> {
<span class="prelude-val">Err</span>(<span class="string">"expected ')'"</span>.<span class="ident">into</span>())
}
}
<span class="doccomment">/// identifierexpr</span>
<span class="doccomment">/// ::= identifier</span>
<span class="doccomment">/// ::= identifier '(' expression* ')'</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Implement `std::unique_ptr<ExprAST> ParseIdentifierExpr();` from the tutorial.</span>
<span class="kw">fn</span> <span class="ident">parse_identifier_expr</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">ParseResult</span><span class="op"><</span><span class="ident">ExprAST</span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">id_name</span> <span class="op">=</span> <span class="kw">match</span> <span class="self">self</span>.<span class="ident">cur_tok</span>.<span class="ident">take</span>() {
<span class="prelude-val">Some</span>(<span class="ident">Token::Identifier</span>(<span class="ident">id</span>)) <span class="op">=</span><span class="op">></span> {
<span class="comment">// Consume identifier.</span>
<span class="self">self</span>.<span class="ident">get_next_token</span>();
<span class="ident">id</span>
}
<span class="kw">_</span> <span class="op">=</span><span class="op">></span> <span class="macro">unreachable!</span>(),
};
<span class="kw">if</span> <span class="kw-2">*</span><span class="self">self</span>.<span class="ident">cur_tok</span>() <span class="op">!</span><span class="op">=</span> <span class="ident">Token::Char</span>(<span class="string">'('</span>) {
<span class="comment">// Simple variable reference.</span>
<span class="prelude-val">Ok</span>(<span class="ident">ExprAST::Variable</span>(<span class="ident">id_name</span>))
} <span class="kw">else</span> {
<span class="comment">// Call.</span>
<span class="comment">// Eat '(' token.</span>
<span class="self">self</span>.<span class="ident">get_next_token</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">args</span>: <span class="ident">Vec</span><span class="op"><</span><span class="ident">ExprAST</span><span class="op">></span> <span class="op">=</span> <span class="ident">Vec::new</span>();
<span class="comment">// If there are arguments collect them.</span>
<span class="kw">if</span> <span class="kw-2">*</span><span class="self">self</span>.<span class="ident">cur_tok</span>() <span class="op">!</span><span class="op">=</span> <span class="ident">Token::Char</span>(<span class="string">')'</span>) {
<span class="kw">loop</span> {
<span class="kw">let</span> <span class="ident">arg</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">parse_expression</span>()<span class="question-mark">?</span>;
<span class="ident">args</span>.<span class="ident">push</span>(<span class="ident">arg</span>);
<span class="kw">if</span> <span class="kw-2">*</span><span class="self">self</span>.<span class="ident">cur_tok</span>() <span class="op">=</span><span class="op">=</span> <span class="ident">Token::Char</span>(<span class="string">')'</span>) {
<span class="comment">// Eat ')' token.</span>
<span class="self">self</span>.<span class="ident">get_next_token</span>();
<span class="kw">break</span>;
}
<span class="kw">if</span> <span class="kw-2">*</span><span class="self">self</span>.<span class="ident">cur_tok</span>() <span class="op">!</span><span class="op">=</span> <span class="ident">Token::Char</span>(<span class="string">','</span>) {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="string">"Expected ')' or ',' in argument list"</span>.<span class="ident">into</span>());
}
<span class="self">self</span>.<span class="ident">get_next_token</span>();
}
}
<span class="prelude-val">Ok</span>(<span class="ident">ExprAST::Call</span>(<span class="ident">id_name</span>, <span class="ident">args</span>))
}
}
<span class="doccomment">/// primary</span>
<span class="doccomment">/// ::= identifierexpr</span>
<span class="doccomment">/// ::= numberexpr</span>
<span class="doccomment">/// ::= parenexpr</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Implement `std::unique_ptr<ExprAST> ParsePrimary();` from the tutorial.</span>
<span class="kw">fn</span> <span class="ident">parse_primary</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">ParseResult</span><span class="op"><</span><span class="ident">ExprAST</span><span class="op">></span> {
<span class="kw">match</span> <span class="kw-2">*</span><span class="self">self</span>.<span class="ident">cur_tok</span>() {
<span class="ident">Token::Identifier</span>(<span class="kw">_</span>) <span class="op">=</span><span class="op">></span> <span class="self">self</span>.<span class="ident">parse_identifier_expr</span>(),
<span class="ident">Token::Number</span>(<span class="kw">_</span>) <span class="op">=</span><span class="op">></span> <span class="self">self</span>.<span class="ident">parse_num_expr</span>(),
<span class="ident">Token::Char</span>(<span class="string">'('</span>) <span class="op">=</span><span class="op">></span> <span class="self">self</span>.<span class="ident">parse_paren_expr</span>(),
<span class="kw">_</span> <span class="op">=</span><span class="op">></span> <span class="prelude-val">Err</span>(<span class="string">"unknown token when expecting an expression"</span>.<span class="ident">into</span>()),
}
}
<span class="comment">// -----------------------------</span>
<span class="comment">// Binary Expression Parsing</span>
<span class="comment">// -----------------------------</span>
<span class="doccomment">/// /// expression</span>
<span class="doccomment">/// ::= primary binoprhs</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Implement `std::unique_ptr<ExprAST> ParseExpression();` from the tutorial.</span>
<span class="kw">fn</span> <span class="ident">parse_expression</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">ParseResult</span><span class="op"><</span><span class="ident">ExprAST</span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">lhs</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">parse_primary</span>()<span class="question-mark">?</span>;
<span class="self">self</span>.<span class="ident">parse_bin_op_rhs</span>(<span class="number">0</span>, <span class="ident">lhs</span>)
}
<span class="doccomment">/// binoprhs</span>
<span class="doccomment">/// ::= ('+' primary)*</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Implement `std::unique_ptr<ExprAST> ParseBinOpRHS(int ExprPrec, std::unique_ptr<ExprAST> LHS);` from the tutorial.</span>
<span class="kw">fn</span> <span class="ident">parse_bin_op_rhs</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">expr_prec</span>: <span class="ident">isize</span>, <span class="kw-2">mut</span> <span class="ident">lhs</span>: <span class="ident">ExprAST</span>) <span class="op">-</span><span class="op">></span> <span class="ident">ParseResult</span><span class="op"><</span><span class="ident">ExprAST</span><span class="op">></span> {
<span class="kw">loop</span> {
<span class="kw">let</span> <span class="ident">tok_prec</span> <span class="op">=</span> <span class="ident">get_tok_precedence</span>(<span class="self">self</span>.<span class="ident">cur_tok</span>());
<span class="comment">// Not a binary operator or precedence is too small.</span>
<span class="kw">if</span> <span class="ident">tok_prec</span> <span class="op"><</span> <span class="ident">expr_prec</span> {
<span class="kw">return</span> <span class="prelude-val">Ok</span>(<span class="ident">lhs</span>);
}
<span class="kw">let</span> <span class="ident">binop</span> <span class="op">=</span> <span class="kw">match</span> <span class="self">self</span>.<span class="ident">cur_tok</span>.<span class="ident">take</span>() {
<span class="prelude-val">Some</span>(<span class="ident">Token::Char</span>(<span class="ident">c</span>)) <span class="op">=</span><span class="op">></span> {
<span class="comment">// Eat binary operator.</span>
<span class="self">self</span>.<span class="ident">get_next_token</span>();
<span class="ident">c</span>
}
<span class="kw">_</span> <span class="op">=</span><span class="op">></span> <span class="macro">unreachable!</span>(),
};
<span class="comment">// lhs BINOP1 rhs BINOP2 remrhs</span>
<span class="comment">// ^^^^^^ ^^^^^^</span>
<span class="comment">// tok_prec next_prec</span>
<span class="comment">//</span>
<span class="comment">// In case BINOP1 has higher precedence, we are done here and can build a 'Binary' AST</span>
<span class="comment">// node between 'lhs' and 'rhs'.</span>
<span class="comment">//</span>
<span class="comment">// In case BINOP2 has higher precedence, we take 'rhs' as 'lhs' and recurse into the</span>
<span class="comment">// 'remrhs' expression first.</span>
<span class="comment">// Parse primary expression after binary operator.</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">rhs</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">parse_primary</span>()<span class="question-mark">?</span>;
<span class="kw">let</span> <span class="ident">next_prec</span> <span class="op">=</span> <span class="ident">get_tok_precedence</span>(<span class="self">self</span>.<span class="ident">cur_tok</span>());
<span class="kw">if</span> <span class="ident">tok_prec</span> <span class="op"><</span> <span class="ident">next_prec</span> {
<span class="comment">// BINOP2 has higher precedence thatn BINOP1, recurse into 'remhs'.</span>
<span class="ident">rhs</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">parse_bin_op_rhs</span>(<span class="ident">tok_prec</span> <span class="op">+</span> <span class="number">1</span>, <span class="ident">rhs</span>)<span class="question-mark">?</span>
}
<span class="ident">lhs</span> <span class="op">=</span> <span class="ident">ExprAST::Binary</span>(<span class="ident">binop</span>, <span class="ident">Box::new</span>(<span class="ident">lhs</span>), <span class="ident">Box::new</span>(<span class="ident">rhs</span>));
}
}
<span class="comment">// --------------------</span>
<span class="comment">// Parsing the Rest</span>
<span class="comment">// --------------------</span>
<span class="doccomment">/// prototype</span>
<span class="doccomment">/// ::= id '(' id* ')'</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Implement `std::unique_ptr<PrototypeAST> ParsePrototype();` from the tutorial.</span>
<span class="kw">fn</span> <span class="ident">parse_prototype</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">ParseResult</span><span class="op"><</span><span class="ident">PrototypeAST</span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">id_name</span> <span class="op">=</span> <span class="kw">match</span> <span class="self">self</span>.<span class="ident">cur_tok</span>.<span class="ident">take</span>() {
<span class="prelude-val">Some</span>(<span class="ident">Token::Identifier</span>(<span class="ident">id</span>)) <span class="op">=</span><span class="op">></span> {
<span class="comment">// Consume the identifier.</span>
<span class="self">self</span>.<span class="ident">get_next_token</span>();
<span class="ident">id</span>
}
<span class="ident">other</span> <span class="op">=</span><span class="op">></span> {
<span class="comment">// Plug back current token.</span>
<span class="self">self</span>.<span class="ident">cur_tok</span> <span class="op">=</span> <span class="ident">other</span>;
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="string">"Expected function name in prototype"</span>.<span class="ident">into</span>());
}
};
<span class="kw">if</span> <span class="kw-2">*</span><span class="self">self</span>.<span class="ident">cur_tok</span>() <span class="op">!</span><span class="op">=</span> <span class="ident">Token::Char</span>(<span class="string">'('</span>) {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="string">"Expected '(' in prototype"</span>.<span class="ident">into</span>());
}
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">args</span>: <span class="ident">Vec</span><span class="op"><</span><span class="ident">String</span><span class="op">></span> <span class="op">=</span> <span class="ident">Vec::new</span>();
<span class="kw">loop</span> {
<span class="self">self</span>.<span class="ident">get_next_token</span>();
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">cur_tok</span>.<span class="ident">take</span>() {
<span class="prelude-val">Some</span>(<span class="ident">Token::Identifier</span>(<span class="ident">arg</span>)) <span class="op">=</span><span class="op">></span> <span class="ident">args</span>.<span class="ident">push</span>(<span class="ident">arg</span>),
<span class="prelude-val">Some</span>(<span class="ident">Token::Char</span>(<span class="string">','</span>)) <span class="op">=</span><span class="op">></span> {}
<span class="ident">other</span> <span class="op">=</span><span class="op">></span> {
<span class="self">self</span>.<span class="ident">cur_tok</span> <span class="op">=</span> <span class="ident">other</span>;
<span class="kw">break</span>;
}
}
}
<span class="kw">if</span> <span class="kw-2">*</span><span class="self">self</span>.<span class="ident">cur_tok</span>() <span class="op">!</span><span class="op">=</span> <span class="ident">Token::Char</span>(<span class="string">')'</span>) {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="string">"Expected ')' in prototype"</span>.<span class="ident">into</span>());
}
<span class="comment">// Consume ')'.</span>
<span class="self">self</span>.<span class="ident">get_next_token</span>();
<span class="prelude-val">Ok</span>(<span class="ident">PrototypeAST</span>(<span class="ident">id_name</span>, <span class="ident">args</span>))
}
<span class="doccomment">/// definition ::= 'def' prototype expression</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Implement `std::unique_ptr<FunctionAST> ParseDefinition();` from the tutorial.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">parse_definition</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">ParseResult</span><span class="op"><</span><span class="ident">FunctionAST</span><span class="op">></span> {
<span class="comment">// Consume 'def' token.</span>
<span class="macro">assert_eq!</span>(<span class="kw-2">*</span><span class="self">self</span>.<span class="ident">cur_tok</span>(), <span class="ident">Token::Def</span>);
<span class="self">self</span>.<span class="ident">get_next_token</span>();
<span class="kw">let</span> <span class="ident">proto</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">parse_prototype</span>()<span class="question-mark">?</span>;
<span class="kw">let</span> <span class="ident">expr</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">parse_expression</span>()<span class="question-mark">?</span>;
<span class="prelude-val">Ok</span>(<span class="ident">FunctionAST</span>(<span class="ident">proto</span>, <span class="ident">expr</span>))
}
<span class="doccomment">/// external ::= 'extern' prototype</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Implement `std::unique_ptr<PrototypeAST> ParseExtern();` from the tutorial.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">parse_extern</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">ParseResult</span><span class="op"><</span><span class="ident">PrototypeAST</span><span class="op">></span> {
<span class="comment">// Consume 'extern' token.</span>
<span class="macro">assert_eq!</span>(<span class="kw-2">*</span><span class="self">self</span>.<span class="ident">cur_tok</span>(), <span class="ident">Token::Extern</span>);
<span class="self">self</span>.<span class="ident">get_next_token</span>();
<span class="self">self</span>.<span class="ident">parse_prototype</span>()
}
<span class="doccomment">/// toplevelexpr ::= expression</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Implement `std::unique_ptr<FunctionAST> ParseTopLevelExpr();` from the tutorial.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">parse_top_level_expr</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">ParseResult</span><span class="op"><</span><span class="ident">FunctionAST</span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">e</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">parse_expression</span>()<span class="question-mark">?</span>;
<span class="kw">let</span> <span class="ident">proto</span> <span class="op">=</span> <span class="ident">PrototypeAST</span>(<span class="string">""</span>.<span class="ident">into</span>(), <span class="ident">Vec::new</span>());
<span class="prelude-val">Ok</span>(<span class="ident">FunctionAST</span>(<span class="ident">proto</span>, <span class="ident">e</span>))
}
}
<span class="doccomment">/// Get the binary operator precedence.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Implement `int GetTokPrecedence();` from the tutorial.</span>
<span class="kw">fn</span> <span class="ident">get_tok_precedence</span>(<span class="ident">tok</span>: <span class="kw-2">&</span><span class="ident">Token</span>) <span class="op">-</span><span class="op">></span> <span class="ident">isize</span> {
<span class="kw">match</span> <span class="ident">tok</span> {
<span class="ident">Token::Char</span>(<span class="string">'<'</span>) <span class="op">=</span><span class="op">></span> <span class="number">10</span>,
<span class="ident">Token::Char</span>(<span class="string">'+'</span>) <span class="op">=</span><span class="op">></span> <span class="number">20</span>,
<span class="ident">Token::Char</span>(<span class="string">'-'</span>) <span class="op">=</span><span class="op">></span> <span class="number">20</span>,
<span class="ident">Token::Char</span>(<span class="string">'*'</span>) <span class="op">=</span><span class="op">></span> <span class="number">40</span>,
<span class="kw">_</span> <span class="op">=</span><span class="op">></span> <span class="op">-</span><span class="number">1</span>,
}
}
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">test</span>)]</span>
<span class="kw">mod</span> <span class="ident">test</span> {
<span class="kw">use</span> <span class="kw">super</span>::{<span class="ident">ExprAST</span>, <span class="ident">FunctionAST</span>, <span class="ident">Parser</span>, <span class="ident">PrototypeAST</span>};
<span class="kw">use</span> <span class="kw">crate</span><span class="ident">::lexer::Lexer</span>;
<span class="kw">fn</span> <span class="ident">parser</span>(<span class="ident">input</span>: <span class="kw-2">&</span><span class="ident">str</span>) <span class="op">-</span><span class="op">></span> <span class="ident">Parser</span><span class="op"><</span><span class="ident">std::str::Chars</span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">l</span> <span class="op">=</span> <span class="ident">Lexer::new</span>(<span class="ident">input</span>.<span class="ident">chars</span>());
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">p</span> <span class="op">=</span> <span class="ident">Parser::new</span>(<span class="ident">l</span>);
<span class="comment">// Drop initial coin, initialize cur_tok.</span>
<span class="ident">p</span>.<span class="ident">get_next_token</span>();
<span class="ident">p</span>
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">parse_number</span>() {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">p</span> <span class="op">=</span> <span class="ident">parser</span>(<span class="string">"13.37"</span>);
<span class="macro">assert_eq!</span>(<span class="ident">p</span>.<span class="ident">parse_num_expr</span>(), <span class="prelude-val">Ok</span>(<span class="ident">ExprAST::Number</span>(<span class="number">13.37f64</span>)));
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">parse_variable</span>() {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">p</span> <span class="op">=</span> <span class="ident">parser</span>(<span class="string">"foop"</span>);
<span class="macro">assert_eq!</span>(
<span class="ident">p</span>.<span class="ident">parse_identifier_expr</span>(),
<span class="prelude-val">Ok</span>(<span class="ident">ExprAST::Variable</span>(<span class="string">"foop"</span>.<span class="ident">into</span>()))
);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">parse_primary</span>() {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">p</span> <span class="op">=</span> <span class="ident">parser</span>(<span class="string">"1337 foop \n bla(123)"</span>);
<span class="macro">assert_eq!</span>(<span class="ident">p</span>.<span class="ident">parse_primary</span>(), <span class="prelude-val">Ok</span>(<span class="ident">ExprAST::Number</span>(<span class="number">1337f64</span>)));
<span class="macro">assert_eq!</span>(<span class="ident">p</span>.<span class="ident">parse_primary</span>(), <span class="prelude-val">Ok</span>(<span class="ident">ExprAST::Variable</span>(<span class="string">"foop"</span>.<span class="ident">into</span>())));
<span class="macro">assert_eq!</span>(
<span class="ident">p</span>.<span class="ident">parse_primary</span>(),
<span class="prelude-val">Ok</span>(<span class="ident">ExprAST::Call</span>(<span class="string">"bla"</span>.<span class="ident">into</span>(), <span class="macro">vec!</span>[<span class="ident">ExprAST::Number</span>(<span class="number">123f64</span>)]))
);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">parse_binary_op</span>() {
<span class="comment">// Operator before RHS has higher precedence, expected AST</span>
<span class="comment">//</span>
<span class="comment">// -</span>
<span class="comment">// / \</span>
<span class="comment">// + c</span>
<span class="comment">// / \</span>
<span class="comment">// a b</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">p</span> <span class="op">=</span> <span class="ident">parser</span>(<span class="string">"a + b - c"</span>);
<span class="kw">let</span> <span class="ident">binexpr_ab</span> <span class="op">=</span> <span class="ident">ExprAST::Binary</span>(
<span class="string">'+'</span>,
<span class="ident">Box::new</span>(<span class="ident">ExprAST::Variable</span>(<span class="string">"a"</span>.<span class="ident">into</span>())),
<span class="ident">Box::new</span>(<span class="ident">ExprAST::Variable</span>(<span class="string">"b"</span>.<span class="ident">into</span>())),
);
<span class="kw">let</span> <span class="ident">binexpr_abc</span> <span class="op">=</span> <span class="ident">ExprAST::Binary</span>(
<span class="string">'-'</span>,
<span class="ident">Box::new</span>(<span class="ident">binexpr_ab</span>),
<span class="ident">Box::new</span>(<span class="ident">ExprAST::Variable</span>(<span class="string">"c"</span>.<span class="ident">into</span>())),
);
<span class="macro">assert_eq!</span>(<span class="ident">p</span>.<span class="ident">parse_expression</span>(), <span class="prelude-val">Ok</span>(<span class="ident">binexpr_abc</span>));
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">parse_binary_op2</span>() {
<span class="comment">// Operator after RHS has higher precedence, expected AST</span>
<span class="comment">//</span>
<span class="comment">// +</span>
<span class="comment">// / \</span>
<span class="comment">// a *</span>
<span class="comment">// / \</span>
<span class="comment">// b c</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">p</span> <span class="op">=</span> <span class="ident">parser</span>(<span class="string">"a + b * c"</span>);
<span class="kw">let</span> <span class="ident">binexpr_bc</span> <span class="op">=</span> <span class="ident">ExprAST::Binary</span>(
<span class="string">'*'</span>,
<span class="ident">Box::new</span>(<span class="ident">ExprAST::Variable</span>(<span class="string">"b"</span>.<span class="ident">into</span>())),
<span class="ident">Box::new</span>(<span class="ident">ExprAST::Variable</span>(<span class="string">"c"</span>.<span class="ident">into</span>())),
);
<span class="kw">let</span> <span class="ident">binexpr_abc</span> <span class="op">=</span> <span class="ident">ExprAST::Binary</span>(
<span class="string">'+'</span>,
<span class="ident">Box::new</span>(<span class="ident">ExprAST::Variable</span>(<span class="string">"a"</span>.<span class="ident">into</span>())),
<span class="ident">Box::new</span>(<span class="ident">binexpr_bc</span>),
);
<span class="macro">assert_eq!</span>(<span class="ident">p</span>.<span class="ident">parse_expression</span>(), <span class="prelude-val">Ok</span>(<span class="ident">binexpr_abc</span>));
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">parse_prototype</span>() {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">p</span> <span class="op">=</span> <span class="ident">parser</span>(<span class="string">"foo(a,b)"</span>);
<span class="kw">let</span> <span class="ident">proto</span> <span class="op">=</span> <span class="ident">PrototypeAST</span>(<span class="string">"foo"</span>.<span class="ident">into</span>(), <span class="macro">vec!</span>[<span class="string">"a"</span>.<span class="ident">into</span>(), <span class="string">"b"</span>.<span class="ident">into</span>()]);
<span class="macro">assert_eq!</span>(<span class="ident">p</span>.<span class="ident">parse_prototype</span>(), <span class="prelude-val">Ok</span>(<span class="ident">proto</span>));
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">parse_definition</span>() {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">p</span> <span class="op">=</span> <span class="ident">parser</span>(<span class="string">"def bar( arg0 , arg1 ) arg0 + arg1"</span>);
<span class="kw">let</span> <span class="ident">proto</span> <span class="op">=</span> <span class="ident">PrototypeAST</span>(<span class="string">"bar"</span>.<span class="ident">into</span>(), <span class="macro">vec!</span>[<span class="string">"arg0"</span>.<span class="ident">into</span>(), <span class="string">"arg1"</span>.<span class="ident">into</span>()]);
<span class="kw">let</span> <span class="ident">body</span> <span class="op">=</span> <span class="ident">ExprAST::Binary</span>(
<span class="string">'+'</span>,
<span class="ident">Box::new</span>(<span class="ident">ExprAST::Variable</span>(<span class="string">"arg0"</span>.<span class="ident">into</span>())),
<span class="ident">Box::new</span>(<span class="ident">ExprAST::Variable</span>(<span class="string">"arg1"</span>.<span class="ident">into</span>())),
);
<span class="kw">let</span> <span class="ident">func</span> <span class="op">=</span> <span class="ident">FunctionAST</span>(<span class="ident">proto</span>, <span class="ident">body</span>);
<span class="macro">assert_eq!</span>(<span class="ident">p</span>.<span class="ident">parse_definition</span>(), <span class="prelude-val">Ok</span>(<span class="ident">func</span>));
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">parse_extern</span>() {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">p</span> <span class="op">=</span> <span class="ident">parser</span>(<span class="string">"extern baz()"</span>);
<span class="kw">let</span> <span class="ident">proto</span> <span class="op">=</span> <span class="ident">PrototypeAST</span>(<span class="string">"baz"</span>.<span class="ident">into</span>(), <span class="macro">vec!</span>[]);
<span class="macro">assert_eq!</span>(<span class="ident">p</span>.<span class="ident">parse_extern</span>(), <span class="prelude-val">Ok</span>(<span class="ident">proto</span>));
}
}
</pre></div>
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