1 | /**
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2 | * @fileoverview Require or disallow Unicode BOM
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3 | * @author Andrew Johnston <https://github.com/ehjay>
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4 | */
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5 | ;
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6 |
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7 | //------------------------------------------------------------------------------
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8 | // Rule Definition
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9 | //------------------------------------------------------------------------------
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10 |
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11 | module.exports = {
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12 | meta: {
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13 | type: "layout",
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14 |
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15 | docs: {
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16 | description: "require or disallow Unicode byte order mark (BOM)",
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17 | category: "Stylistic Issues",
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18 | recommended: false,
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19 | url: "https://eslint.org/docs/rules/unicode-bom"
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20 | },
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21 |
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22 | fixable: "whitespace",
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23 |
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24 | schema: [
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25 | {
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26 | enum: ["always", "never"]
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27 | }
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28 | ],
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29 | messages: {
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30 | expected: "Expected Unicode BOM (Byte Order Mark).",
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31 | unexpected: "Unexpected Unicode BOM (Byte Order Mark)."
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32 | }
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33 | },
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34 |
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35 | create(context) {
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36 |
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37 | //--------------------------------------------------------------------------
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38 | // Public
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39 | //--------------------------------------------------------------------------
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40 |
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41 | return {
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42 |
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43 | Program: function checkUnicodeBOM(node) {
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44 |
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45 | const sourceCode = context.getSourceCode(),
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46 | location = { column: 0, line: 1 },
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47 | requireBOM = context.options[0] || "never";
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48 |
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49 | if (!sourceCode.hasBOM && (requireBOM === "always")) {
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50 | context.report({
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51 | node,
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52 | loc: location,
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53 | messageId: "expected",
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54 | fix(fixer) {
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55 | return fixer.insertTextBeforeRange([0, 1], "\uFEFF");
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56 | }
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57 | });
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58 | } else if (sourceCode.hasBOM && (requireBOM === "never")) {
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59 | context.report({
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60 | node,
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61 | loc: location,
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62 | messageId: "unexpected",
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63 | fix(fixer) {
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64 | return fixer.removeRange([-1, 0]);
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65 | }
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66 | });
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67 | }
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68 | }
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69 |
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70 | };
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71 |
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72 | }
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73 | };
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