example http parser
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cozis
@@ -0,0 +1,383 @@
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scan = import("scan.noja");
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newScanner = scan.newScanner;
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Scanner = scan.Scanner;
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hint = scan.hint;
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consume = scan.consume;
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current = scan.current;
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isDigit = scan.isDigit;
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consumeSpaces = scan.consumeSpaces;
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fun isAlpha(char: String)
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return (string.ord(char) >= string.ord('a') and string.ord(char) <= string.ord('z'))
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or (string.ord(char) >= string.ord('A') and string.ord(char) <= string.ord('Z'));
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fun isUpper(char: String)
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return string.ord(char) >= string.ord('A')
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and string.ord(char) <= string.ord('Z');
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fun isUnreserved(char: String)
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return isAlpha(char)
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or isDigit(char)
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or char == "-"
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or char == "."
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or char == "_"
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or char == "~";
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fun isSubdelim(char: String)
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return char == "!" or char == "$"
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or char == "&" or char == "'"
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or char == "(" or char == ")"
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or char == "*" or char == "+"
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or char == "," or char == ";"
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or char == "=";
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fun isPChar(char: String)
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return isUnreserved(char)
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or isSubdelim(char)
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or char == ":"
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or char == "@";
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fun parseMethod(scan: Scanner) {
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char = current(scan);
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if char == none or not isUpper(char):
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return none, "Missing method";
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method = "";
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do {
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method = string.cat(method, char);
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consume(scan);
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char = current(scan);
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} while char != none and isUpper(char);
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return method, none;
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}
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fun parsePort(scan: Scanner) {
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port = none;
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char = current(scan);
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if char == ":" and isDigit(hint(scan, 1)): {
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consume(scan); # Skip the ":"
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char = current(scan);
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port = 0;
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do {
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digit = string.ord(char)
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- string.ord("0");
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port = port * 10 + digit;
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consume(scan);
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char = current(scan);
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} while char != none and isDigit(char);
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}
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return port;
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}
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fun isHostname(char: String)
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return isUnreserved(char)
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or isSubdelim(char);
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fun parseHost(scan: Scanner) {
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char = current(scan);
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if char == none:
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return none, "Missing host";
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if not isHostname(char):
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return none, "Invalid character in place of host";
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name = "";
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do {
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name = string.cat(name, char);
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consume(scan);
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char = current(scan);
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} while char != none and isHostname(char);
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port = parsePort(scan);
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return {name: name, port: port};
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}
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fun parsePath(scan: Scanner) {
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path = "";
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char = current(scan);
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if char != none and char == "/": {
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path = string.cat(path, char);
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consume(scan);
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char = current(scan);
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} else {
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if char == none or not isPChar(char):
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return none, "Invalid character in place of path";
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}
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while char != none and isPChar(char): {
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do {
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path = string.cat(path, char);
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consume(scan);
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char = current(scan);
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} while char != none and isPChar(char);
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if char == none or char != "/":
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break;
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path = string.cat(path, char);
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consume(scan);
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char = current(scan);
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}
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return path;
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}
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fun isQuery(char: ?String) {
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if char == none:
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return false;
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return isPChar(char)
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or char == "/"
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or char == "?";
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}
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fun parseQuery(scan: Scanner) {
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char = current(scan);
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if char != none and char == "?": {
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consume(scan); # Consume the "?"
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query = "";
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while isQuery(char = current(scan)): {
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query = string.cat(query, char);
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consume(scan);
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}
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} else
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query = none;
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return query;
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}
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fun isFragment(char: ?String) {
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if char == none:
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return false;
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return isPChar(char) or char == "/";
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}
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fun parseFragment(scan: Scanner) {
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char = current(scan);
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if char != none and char == "#": {
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consume(scan); # Consume the "#"
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fragment = "";
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while isFragment(char = current(scan)): {
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fragment = string.cat(fragment, char);
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consume(scan);
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}
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} else
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fragment = none;
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return fragment;
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}
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Host = { name: String, port: ?int };
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URL = {
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schema: ?String,
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host: ?Host,
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path: ?String,
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query: ?String,
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fragment: ?String
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};
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fun isSchemaFirst(char: ?String) {
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return char != none and isAlpha(char);
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}
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fun isSchema(char: ?String)
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return char != none
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and (isAlpha(char)
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or isDigit(char)
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or char == "+"
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or char == "-"
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or char == ".");
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fun parseSchema(scan: Scanner) {
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char = current(scan);
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schema = none;
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if isSchemaFirst(char): {
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start = scan.i;
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schema = "";
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do {
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schema = string.cat(schema, char);
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consume(scan);
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char = current(scan);
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} while isSchema(char);
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if char == ":":
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consume(scan);
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else {
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schema = none;
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scan.i = start;
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}
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}
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return schema;
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}
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fun followsAuthority(scan: Scanner)
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return current(scan) == "/" and hint(scan, 1) == "/";
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fun parseURL(scan: Scanner) {
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schema = parseSchema(scan);
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if followsAuthority(scan): {
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consume(scan, 2);
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host, error = parseHost(scan);
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if error != none:
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return none, error;
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path = none;
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if current(scan) == "/":
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path = parsePath(scan);
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} else {
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host = none;
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char = current(scan);
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if char == none or char == "?" or char == "#":
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return none, "Missing path";
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path, error = parsePath(scan);
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if error != none:
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return none, error;
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}
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query = parseQuery(scan);
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fragment = parseFragment(scan);
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print(scan);
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return {
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host : host,
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path : path,
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query : query,
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schema : schema,
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fragment: fragment
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};
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}
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fun parseVersion(scan: Scanner) {
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if hint(scan, 0) != "H" or hint(scan, 1) != "T"
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or hint(scan, 2) != "T" or hint(scan, 3) != "P"
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or hint(scan, 4) != "/" or not isDigit(hint(scan, 5)):
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return none, "Invalid version token";
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consume(scan, 5);
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major = string.ord(current(scan))
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- string.ord("0");
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if hint(scan, 1) != "." and isDigit(hint(scan, 2)): {
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consume(scan, 2);
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minor = string.ord(current(scan))
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- string.ord("0");
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} else
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minor = 0;
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consume(scan);
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return {major: major, minor: minor};
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}
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Version = {
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major: int,
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minor: int
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};
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Request = {
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method : String,
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url : URL,
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version: Version
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};
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fun newRequest(method: String, url: URL,
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version: Version, headers: Map = {})
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return {
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method: method,
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url: url,
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version: version,
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headers: headers
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};
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fun parse(src: String) {
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scan = newScanner(src);
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method, error = parseMethod(scan);
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if error != none:
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return none, error;
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char = current(scan);
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if char == none or char != " ":
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return none, "Missing space after method";
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consume(scan);
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url, error = parseURL(scan);
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if error != none:
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return none, error;
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char = current(scan);
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if char != " ":
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return none, "Missing space after URL";
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consume(scan);
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version, error = parseVersion(scan);
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if error != none:
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return none, error;
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if hint(scan, 0) != "\r" or hint(scan, 1) != "\n":
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# Request with no headers or body
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return newRequest(method, url, version);
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consume(scan, 2); # Consume the "\r\n"
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headers = {};
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while (char = hint(scan, 0)) != none and (char != "\r" or hint(scan, 1) != "\n"): {
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# Header name until the next ":"
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name = "";
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do {
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name = string.cat(name, char);
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consume(scan);
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char = current(scan);
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} while char != ":" and char != none;
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if char == none:
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return none, "Invalid header (missing \":\" after name)";
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consume(scan);
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consumeSpaces(scan);
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char = current(scan);
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# Header body until \r
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body = "";
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do {
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body = string.cat(body, char);
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consume(scan);
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char = current(scan);
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} while char != "\r" and char != none;
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headers[name] = body;
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}
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if char != none:
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consume(scan, 2); # Consume the final "\r\n"
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return newRequest(method, url, version, headers);
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}
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sample = string.cat(
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"GET /search?client=firefox-b-d&q=http+request+dataset HTTP/2\r\n",
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"Host: www.google.com\r\n",
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"user-agent: curl/7.84.0\r\n",
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"accept: */*\r\n",
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"\r\n");
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request, error = parse(sample);
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print("request=", request, "\n");
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print("error=", error, "\n");
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