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79 lines
3.2 KiB
C#
79 lines
3.2 KiB
C#
/*
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* Copyright 2018 faddenSoft
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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using System;
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using System.Text.RegularExpressions;
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namespace Asm65 {
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/// <summary>
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/// Utility classes for working with labels.
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///
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/// The decision of whether to treat labels as case-sensitive or case-insensitive is
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/// encapsulated here. All code should be case-preserving, but the comparison method
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/// and "normal form" are defined here.
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/// </summary>
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public class Label {
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// Arbitrary choice for SourceGen. Different assemblers have different limits.
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public const int MAX_LABEL_LEN = 32;
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public const bool LABELS_CASE_SENSITIVE = true;
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/// <summary>
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/// String comparer to use when comparing labels.
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///
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/// We may want case-insensitive string compares, and we want the "invariant culture"
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/// version for consistent results across users in multiple locales. (The labels are
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/// expected to be ASCII strings, so the latter isn't crucial unless we change the
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/// allowed set.)
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/// </summary>
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public static readonly StringComparer LABEL_COMPARER = LABELS_CASE_SENSITIVE ?
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StringComparer.InvariantCulture :
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StringComparer.InvariantCultureIgnoreCase;
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/// <summary>
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/// Regex pattern for a valid label.
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///
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/// ASCII-only, starts with letter or underscore, followed by at least
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/// one alphanumeric or underscore. Some assemblers may allow single-letter
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/// labels, but I don't want to risk confusion with A/S/X/Y. So either we
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/// reserve those, or we just mandate a two-character minimum.
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/// </summary>
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private static string sValidLabelPattern = @"^[a-zA-Z_][a-zA-Z0-9_]+$";
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private static Regex sValidLabelCharRegex = new Regex(sValidLabelPattern);
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/// <summary>
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/// Validates a label, confirming that it is correctly formed.
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/// </summary>
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/// <param name="label">Label to validate.</param>
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/// <returns>True if the label is correctly formed.</returns>
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public static bool ValidateLabel(string label) {
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if (label.Length > MAX_LABEL_LEN) {
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return false;
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}
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MatchCollection matches = sValidLabelCharRegex.Matches(label);
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return matches.Count == 1;
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}
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/// <summary>
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/// Returns "normal form" of label. This matches LABEL_COMPARER behavior.
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/// </summary>
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/// <param name="label">Label to transform.</param>
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/// <returns>Transformed label.</returns>
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public static string ToNormal(string label) {
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return LABELS_CASE_SENSITIVE ? label : label.ToUpperInvariant();
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}
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}
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}
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