uritemplate
Version:
An UriTemplate implementation of rfc 6570
175 lines (164 loc) • 7.82 kB
JavaScript
/*jshint unused:false */
/*global pctEncoder, operators, charHelper, rfcCharHelper, LiteralExpression, UriTemplate, VariableExpression, UriTemplateError*/
var parse = (function () {
"use strict";
function parseExpression (expressionText) {
var
operator,
varspecs = [],
varspec = null,
varnameStart = null,
maxLengthStart = null,
index,
chr = '';
function closeVarname () {
var varname = expressionText.substring(varnameStart, index);
if (varname.length === 0) {
throw new UriTemplateError({expressionText: expressionText, message: "a varname must be specified", position: index});
}
varspec = {varname: varname, exploded: false, maxLength: null};
varnameStart = null;
}
function closeMaxLength () {
if (maxLengthStart === index) {
throw new UriTemplateError({expressionText: expressionText, message: "after a ':' you have to specify the length", position: index});
}
varspec.maxLength = parseInt(expressionText.substring(maxLengthStart, index), 10);
maxLengthStart = null;
}
operator = (function (operatorText) {
var op = operators.valueOf(operatorText);
if (op === null) {
throw new UriTemplateError({expressionText: expressionText, message: "illegal use of reserved operator", position: index, operator: operatorText});
}
return op;
}(expressionText.charAt(0)));
index = operator.symbol.length;
varnameStart = index;
for (; index < expressionText.length; index += chr.length) {
chr = pctEncoder.pctCharAt(expressionText, index);
if (varnameStart !== null) {
// the spec says: varname = varchar *( ["."] varchar )
// so a dot is allowed except for the first char
if (chr === '.') {
if (varnameStart === index) {
throw new UriTemplateError({expressionText: expressionText, message: "a varname MUST NOT start with a dot", position: index});
}
continue;
}
if (rfcCharHelper.isVarchar(chr)) {
continue;
}
closeVarname();
}
if (maxLengthStart !== null) {
if (index === maxLengthStart && chr === '0') {
throw new UriTemplateError({expressionText: expressionText, message: "A :prefix must not start with digit 0", position: index});
}
if (charHelper.isDigit(chr)) {
if (index - maxLengthStart >= 4) {
throw new UriTemplateError({expressionText: expressionText, message: "A :prefix must have max 4 digits", position: index});
}
continue;
}
closeMaxLength();
}
if (chr === ':') {
if (varspec.maxLength !== null) {
throw new UriTemplateError({expressionText: expressionText, message: "only one :maxLength is allowed per varspec", position: index});
}
if (varspec.exploded) {
throw new UriTemplateError({expressionText: expressionText, message: "an exploeded varspec MUST NOT be varspeced", position: index});
}
maxLengthStart = index + 1;
continue;
}
if (chr === '*') {
if (varspec === null) {
throw new UriTemplateError({expressionText: expressionText, message: "exploded without varspec", position: index});
}
if (varspec.exploded) {
throw new UriTemplateError({expressionText: expressionText, message: "exploded twice", position: index});
}
if (varspec.maxLength) {
throw new UriTemplateError({expressionText: expressionText, message: "an explode (*) MUST NOT follow to a prefix", position: index});
}
varspec.exploded = true;
continue;
}
// the only legal character now is the comma
if (chr === ',') {
varspecs.push(varspec);
varspec = null;
varnameStart = index + 1;
continue;
}
throw new UriTemplateError({expressionText: expressionText, message: "illegal character", character: chr, position: index});
} // for chr
if (varnameStart !== null) {
closeVarname();
}
if (maxLengthStart !== null) {
closeMaxLength();
}
varspecs.push(varspec);
return new VariableExpression(expressionText, operator, varspecs);
}
function parse (uriTemplateText) {
// assert filled string
var
index,
chr,
expressions = [],
braceOpenIndex = null,
literalStart = 0;
for (index = 0; index < uriTemplateText.length; index += 1) {
chr = uriTemplateText.charAt(index);
if (literalStart !== null) {
if (chr === '}') {
throw new UriTemplateError({templateText: uriTemplateText, message: "unopened brace closed", position: index});
}
if (chr === '{') {
if (literalStart < index) {
expressions.push(new LiteralExpression(uriTemplateText.substring(literalStart, index)));
}
literalStart = null;
braceOpenIndex = index;
}
continue;
}
if (braceOpenIndex !== null) {
// here just { is forbidden
if (chr === '{') {
throw new UriTemplateError({templateText: uriTemplateText, message: "brace already opened", position: index});
}
if (chr === '}') {
if (braceOpenIndex + 1 === index) {
throw new UriTemplateError({templateText: uriTemplateText, message: "empty braces", position: braceOpenIndex});
}
try {
expressions.push(parseExpression(uriTemplateText.substring(braceOpenIndex + 1, index)));
}
catch (error) {
if (error.prototype === UriTemplateError.prototype) {
throw new UriTemplateError({templateText: uriTemplateText, message: error.options.message, position: braceOpenIndex + error.options.position, details: error.options});
}
throw error;
}
braceOpenIndex = null;
literalStart = index + 1;
}
continue;
}
throw new Error('reached unreachable code');
}
if (braceOpenIndex !== null) {
throw new UriTemplateError({templateText: uriTemplateText, message: "unclosed brace", position: braceOpenIndex});
}
if (literalStart < uriTemplateText.length) {
expressions.push(new LiteralExpression(uriTemplateText.substr(literalStart)));
}
return new UriTemplate(uriTemplateText, expressions);
}
return parse;
}());