diff options
Diffstat (limited to 'src/main/java/bjc/inflexion/DirectiveIterator.java')
| -rw-r--r-- | src/main/java/bjc/inflexion/DirectiveIterator.java | 128 |
1 files changed, 128 insertions, 0 deletions
diff --git a/src/main/java/bjc/inflexion/DirectiveIterator.java b/src/main/java/bjc/inflexion/DirectiveIterator.java new file mode 100644 index 0000000..9fbed79 --- /dev/null +++ b/src/main/java/bjc/inflexion/DirectiveIterator.java @@ -0,0 +1,128 @@ +/** + * (C) Copyright 2022 Benjamin Culkin. + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +package bjc.inflexion; + +import java.util.Iterator; + +/** + * Performs the parsing of directives from a string. + * + * @author bjculkin + */ +public class DirectiveIterator implements Iterator<String> { + private String strang; + private int pos; + + /** + * Create a new directive iterator over a string. + * + * @param strang + * The string to parse directives from. + */ + public DirectiveIterator(String strang) { + this.strang = strang; + } + + @Override + public boolean hasNext() { + return pos < strang.length(); + } + + @Override + public String next() { + if (!hasNext()) + return null; + + // Directive nesting level + int level = 0; + int prevPos = pos; + + char prevChar = ' '; + boolean parsingVar = false; + + for (; pos < strang.length(); pos++) { + // Backslash escapes a character + if (prevChar == '\\') + continue; + + char c = strang.charAt(pos); + switch (c) { + case '<': + // Stop parsing at the start of a + // directive, unless the directive is + // the first thing in the string. + if (level == 0 && prevPos != pos) { + return strang.substring(prevPos, pos); + } + level += 1; + break; + case '>': + // :ErrorHandling 11/19/18 + if (level == 0) + throw new IllegalArgumentException( + "Attempted to close inflection directive without one open at position " + + prevPos + " in string '" + strang + + "', current token is '" + + strang.substring(prevPos, pos) + "'"); + // Denest a level + level = Math.max(0, level - 1); + // Stop parsing at the end of a + // directive. + if (level == 0) { + // Advance past the '>' + pos += 1; + + return strang.substring(prevPos, pos); + + } + break; + case '$': + // Ignore v-refs when inside a directive + if (level > 0) + break; + // Stop parsing if this isn't at the + // start of a string + if (prevPos != pos) + return strang.substring(prevPos, pos); + parsingVar = true; + break; + case ' ': + // If we're parsing a v-ref, this + // finishes it. + if (parsingVar) + return strang.substring(prevPos, pos); + break; + default: + // Do nothing for ordinary characters + break; + } + } + + /* + * @TODO 11/19/18 Ben Culkin :ErrorHandling Do something better than this + * exception, if possible. + * + * In the rest of the inflection string code, we use the whole 'list of + * errors/warnings' thing. Is there a way to do something similar here? + */ + if (level > 0) + throw new IllegalArgumentException( + "Unclosed inflection directive, starting at position " + prevPos + + " in string '" + strang + "'"); + + return strang.substring(prevPos, pos); + } +}
\ No newline at end of file |