语法分析器（syntax analyzer）【Java实现】

分析器（syntax analyzer）【Java实现】"/>

语法分析器（syntax analyzer）【Java实现】

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import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
import java.util.StringTokenizer;
import java.util.List;
import java.util.ArrayList;
import java.util.Map;
import java.util.HashMap;class Parser {private List<Token> source;private Token token;private int position;static class Node {public NodeType nt;public Node left, right;public String value;Node() {this.nt = null;this.left = null;this.right = null;this.value = null;}Node(NodeType node_type, Node left, Node right, String value) {this.nt = node_type;this.left = left;this.right = right;this.value = value;}public static Node make_node(NodeType nodetype, Node left, Node right) {return new Node(nodetype, left, right, "");}public static Node make_node(NodeType nodetype, Node left) {return new Node(nodetype, left, null, "");}public static Node make_leaf(NodeType nodetype, String value) {return new Node(nodetype, null, null, value);}}static class Token {public TokenType tokentype;public String value;public int line;public int pos;Token(TokenType token, String value, int line, int pos) {this.tokentype = token; this.value = value; this.line = line; this.pos = pos;}@Overridepublic String toString() {return String.format("%5d  %5d %-15s %s", this.line, this.pos, this.tokentype, this.value);}}static enum TokenType {End_of_input(false, false, false, -1, NodeType.nd_None),Op_multiply(false, true, false, 13, NodeType.nd_Mul),Op_divide(false, true, false, 13, NodeType.nd_Div),Op_mod(false, true, false, 13, NodeType.nd_Mod),Op_add(false, true, false, 12, NodeType.nd_Add),Op_subtract(false, true, false, 12, NodeType.nd_Sub),Op_negate(false, false, true, 14, NodeType.nd_Negate),Op_not(false, false, true, 14, NodeType.nd_Not),Op_less(false, true, false, 10, NodeType.nd_Lss),Op_lessequal(false, true, false, 10, NodeType.nd_Leq),Op_greater(false, true, false, 10, NodeType.nd_Gtr),Op_greaterequal(false, true, false, 10, NodeType.nd_Geq),Op_equal(false, true, true, 9, NodeType.nd_Eql),Op_notequal(false, true, false, 9, NodeType.nd_Neq),Op_assign(false, false, false, -1, NodeType.nd_Assign),Op_and(false, true, false, 5, NodeType.nd_And),Op_or(false, true, false, 4, NodeType.nd_Or),Keyword_if(false, false, false, -1, NodeType.nd_If),Keyword_else(false, false, false, -1, NodeType.nd_None),Keyword_while(false, false, false, -1, NodeType.nd_While),Keyword_print(false, false, false, -1, NodeType.nd_None),Keyword_putc(false, false, false, -1, NodeType.nd_None),LeftParen(false, false, false, -1, NodeType.nd_None),RightParen(false, false, false, -1, NodeType.nd_None),LeftBrace(false, false, false, -1, NodeType.nd_None),RightBrace(false, false, false, -1, NodeType.nd_None),Semicolon(false, false, false, -1, NodeType.nd_None),Comma(false, false, false, -1, NodeType.nd_None),Identifier(false, false, false, -1, NodeType.nd_Ident),Integer(false, false, false, -1, NodeType.nd_Integer),String(false, false, false, -1, NodeType.nd_String);private final int precedence;private final boolean right_assoc;private final boolean is_binary;private final boolean is_unary;private final NodeType node_type;TokenType(boolean right_assoc, boolean is_binary, boolean is_unary, int precedence, NodeType node) {this.right_assoc = right_assoc;this.is_binary = is_binary;this.is_unary = is_unary;this.precedence = precedence;this.node_type = node;}boolean isRightAssoc() { return this.right_assoc; }boolean isBinary() { return this.is_binary; }boolean isUnary() { return this.is_unary; }int getPrecedence() { return this.precedence; }NodeType getNodeType() { return this.node_type; }}static enum NodeType {nd_None(""), nd_Ident("Identifier"), nd_String("String"), nd_Integer("Integer"), nd_Sequence("Sequence"), nd_If("If"),nd_Prtc("Prtc"), nd_Prts("Prts"), nd_Prti("Prti"), nd_While("While"),nd_Assign("Assign"), nd_Negate("Negate"), nd_Not("Not"), nd_Mul("Multiply"), nd_Div("Divide"), nd_Mod("Mod"), nd_Add("Add"),nd_Sub("Subtract"), nd_Lss("Less"), nd_Leq("LessEqual"),nd_Gtr("Greater"), nd_Geq("GreaterEqual"), nd_Eql("Equal"), nd_Neq("NotEqual"), nd_And("And"), nd_Or("Or");private final String name;NodeType(String name) {this.name = name;}@Overridepublic String toString() { return this.name; }}static void error(int line, int pos, String msg) {if (line > 0 && pos > 0) {System.out.printf("%s in line %d, pos %d\n", msg, line, pos);} else {System.out.println(msg);}System.exit(1);}Parser(List<Token> source) {this.source = source;this.token = null;this.position = 0;}Token getNextToken() {this.token = this.source.get(this.position++);return this.token;}Node expr(int p) {Node result = null, node;TokenType op;int q;if (this.token.tokentype == TokenType.LeftParen) {result = paren_expr();} else if (this.token.tokentype == TokenType.Op_add || this.token.tokentype == TokenType.Op_subtract) {op = (this.token.tokentype == TokenType.Op_subtract) ? TokenType.Op_negate : TokenType.Op_add;getNextToken();node = expr(TokenType.Op_negate.getPrecedence());result = (op == TokenType.Op_negate) ? Node.make_node(NodeType.nd_Negate, node) : node;} else if (this.token.tokentype == TokenType.Op_not) {getNextToken();result = Node.make_node(NodeType.nd_Not, expr(TokenType.Op_not.getPrecedence()));} else if (this.token.tokentype == TokenType.Identifier) {result = Node.make_leaf(NodeType.nd_Ident, this.token.value);getNextToken();} else if (this.token.tokentype == TokenType.Integer) {result = Node.make_leaf(NodeType.nd_Integer, this.token.value);getNextToken();} else {error(this.token.line, this.token.pos, "Expecting a primary, found: " + this.token.tokentype);}while (this.token.tokentype.isBinary() && this.token.tokentype.getPrecedence() >= p) {op = this.token.tokentype;getNextToken();q = op.getPrecedence();if (!op.isRightAssoc()) {q++;}node = expr(q);result = Node.make_node(op.getNodeType(), result, node);}return result;}Node paren_expr() {expect("paren_expr", TokenType.LeftParen);Node node = expr(0);expect("paren_expr", TokenType.RightParen);return node;}void expect(String msg, TokenType s) {if (this.token.tokentype == s) {getNextToken();return;}error(this.token.line, this.token.pos, msg + ": Expecting '" + s + "', found: '" + this.token.tokentype + "'");}Node stmt() {Node s, s2, t = null, e, v;if (this.token.tokentype == TokenType.Keyword_if) {getNextToken();e = paren_expr();s = stmt();s2 = null;if (this.token.tokentype == TokenType.Keyword_else) {getNextToken();s2 = stmt();}t = Node.make_node(NodeType.nd_If, e, Node.make_node(NodeType.nd_If, s, s2));} else if (this.token.tokentype == TokenType.Keyword_putc) {getNextToken();e = paren_expr();t = Node.make_node(NodeType.nd_Prtc, e);expect("Putc", TokenType.Semicolon);} else if (this.token.tokentype == TokenType.Keyword_print) {getNextToken();expect("Print", TokenType.LeftParen);while (true) {if (this.token.tokentype == TokenType.String) {e = Node.make_node(NodeType.nd_Prts, Node.make_leaf(NodeType.nd_String, this.token.value));getNextToken();} else {e = Node.make_node(NodeType.nd_Prti, expr(0), null);}t = Node.make_node(NodeType.nd_Sequence, t, e);if (this.token.tokentype != TokenType.Comma) {break;}getNextToken();}expect("Print", TokenType.RightParen);expect("Print", TokenType.Semicolon);} else if (this.token.tokentype == TokenType.Semicolon) {getNextToken();} else if (this.token.tokentype == TokenType.Identifier) {v = Node.make_leaf(NodeType.nd_Ident, this.token.value);getNextToken();expect("assign", TokenType.Op_assign);e = expr(0);t = Node.make_node(NodeType.nd_Assign, v, e);expect("assign", TokenType.Semicolon);} else if (this.token.tokentype == TokenType.Keyword_while) {getNextToken();e = paren_expr();s = stmt();t = Node.make_node(NodeType.nd_While, e, s);} else if (this.token.tokentype == TokenType.LeftBrace) {getNextToken();while (this.token.tokentype != TokenType.RightBrace && this.token.tokentype != TokenType.End_of_input) {t = Node.make_node(NodeType.nd_Sequence, t, stmt());}expect("LBrace", TokenType.RightBrace);} else if (this.token.tokentype == TokenType.End_of_input) {} else {error(this.token.line, this.token.pos, "Expecting start of statement, found: " + this.token.tokentype);}return t;}Node parse() {Node t = null;getNextToken();while (this.token.tokentype != TokenType.End_of_input) {t = Node.make_node(NodeType.nd_Sequence, t, stmt());}return t;}void printAST(Node t) {int i = 0;if (t == null) {System.out.println(";");} else {System.out.printf("%-14s", t.nt);if (t.nt == NodeType.nd_Ident || t.nt == NodeType.nd_Integer || t.nt == NodeType.nd_String) {System.out.println(" " + t.value);} else {System.out.println();printAST(t.left);printAST(t.right);}}}public static void main(String[] args) {if (args.length > 0) {try {String value, token;int line, pos;Token t;boolean found;List<Token> list = new ArrayList<>();Map<String, TokenType> str_to_tokens = new HashMap<>();str_to_tokens.put("End_of_input", TokenType.End_of_input);str_to_tokens.put("Op_multiply", TokenType.Op_multiply);str_to_tokens.put("Op_divide", TokenType.Op_divide);str_to_tokens.put("Op_mod", TokenType.Op_mod);str_to_tokens.put("Op_add", TokenType.Op_add);str_to_tokens.put("Op_subtract", TokenType.Op_subtract);str_to_tokens.put("Op_negate", TokenType.Op_negate);str_to_tokens.put("Op_not", TokenType.Op_not);str_to_tokens.put("Op_less", TokenType.Op_less);str_to_tokens.put("Op_lessequal", TokenType.Op_lessequal);str_to_tokens.put("Op_greater", TokenType.Op_greater);str_to_tokens.put("Op_greaterequal", TokenType.Op_greaterequal);str_to_tokens.put("Op_equal", TokenType.Op_equal);str_to_tokens.put("Op_notequal", TokenType.Op_notequal);str_to_tokens.put("Op_assign", TokenType.Op_assign);str_to_tokens.put("Op_and", TokenType.Op_and);str_to_tokens.put("Op_or", TokenType.Op_or);str_to_tokens.put("Keyword_if", TokenType.Keyword_if);str_to_tokens.put("Keyword_else", TokenType.Keyword_else);str_to_tokens.put("Keyword_while", TokenType.Keyword_while);str_to_tokens.put("Keyword_print", TokenType.Keyword_print);str_to_tokens.put("Keyword_putc", TokenType.Keyword_putc);str_to_tokens.put("LeftParen", TokenType.LeftParen);str_to_tokens.put("RightParen", TokenType.RightParen);str_to_tokens.put("LeftBrace", TokenType.LeftBrace);str_to_tokens.put("RightBrace", TokenType.RightBrace);str_to_tokens.put("Semicolon", TokenType.Semicolon);str_to_tokens.put("Comma", TokenType.Comma);str_to_tokens.put("Identifier", TokenType.Identifier);str_to_tokens.put("Integer", TokenType.Integer);str_to_tokens.put("String", TokenType.String);Scanner s = new Scanner(new File(args[0]));String source = " ";while (s.hasNext()) {String str = s.nextLine();StringTokenizer st = new StringTokenizer(str);line = Integer.parseInt(st.nextToken());pos = Integer.parseInt(st.nextToken());token = st.nextToken();value = "";while (st.hasMoreTokens()) {value += st.nextToken() + " ";}found = false;if (str_to_tokens.containsKey(token)) {found = true;list.add(new Token(str_to_tokens.get(token), value, line, pos));}if (found == false) {throw new Exception("Token not found: '" + token + "'");}}Parser p = new Parser(list);p.printAST(p.parse());} catch (FileNotFoundException e) {error(-1, -1, "Exception: " + e.getMessage());} catch (Exception e) {error(-1, -1, "Exception: " + e.getMessage());}} else {error(-1, -1, "No args");}}
}