fix: Improve PRQL syntax highlightning (#5313)

Update prql_highlight_rules.js

Author: vanillajonathan

src/mode/prql_highlight_rules.js

@@ -40,47 +40,73 @@ var PrqlHighlightRules = function() {
     var bidi = "[\\u202A\\u202B\\u202D\\u202E\\u2066\\u2067\\u2068\\u202C\\u2069]";
 
     this.$rules = {
-        start: [{
+        start: [
+        {
             token: "string.start",
-            regex: '"',
+            regex: 's?"',
             next: "string"
+        }, {
+            token: "string.start",
+            regex: 'f"',
+            next: "fstring"
+        }, {
+            token: "string.start",
+            regex: 'r"',
+            next: "rstring"
+        }, {
+            token: "string",
+            start: "'",
+            end: "'"
         }, {
             token: "string.character",
             regex: "'(?:" + escapeRe.source + "|.)'?"
         }, {
-            token : "constant.language",
-            regex : "^" + identifierRe + "*"
+            token: "constant.language",
+            regex: "^" + identifierRe + "*"
         }, {
-            token : "constant.numeric", // hexadecimal, octal and binary
-            regex : /0(?:[xX][0-9a-fA-F]+|[oO][0-7]+|[bB][01]+)\b/
+            token: "constant.numeric", // hexadecimal, octal and binary
+            regex: /0(?:[xX][0-9a-fA-F]+|[oO][0-7]+|[bB][01]+)\b/
         }, {
-            token : "constant.numeric", // decimal integers and floats
-            regex : /(?:\d\d*(?:\.\d*)?|\.\d+)(?:[eE][+-]?\d+\b)?/
+            token: "constant.numeric", // decimal integers and floats
+            regex: /(?:\d\d*(?:\.\d*)?|\.\d+)(?:[eE][+-]?\d+\b)?/
         }, {
             token: "comment.block",
             regex: "#!.*"
         }, {
             token: "comment.line",
             regex: "#.*"
         }, {
-            token : "keyword.operator",
-            regex : /->|=>|==|!=|>=|<=|~=|&&|\|\||\?\?|\/\/|@/
+            token: "keyword.operator",
+            regex: /\|\s*/,
+            next: "pipe"
+        }, {
+            token: "keyword.operator",
+            regex: /->|=>|==|!=|>=|<=|~=|&&|\|\||\?\?|\/\/|@/
         }, {
             token: "invalid.illegal",
             regex: bidi
         }, {
-            token : "punctuation.operator",
-            regex : /[,`]/
+            token: "punctuation.operator",
+            regex: /[,`]/
         }, {
-            token : keywordMapper,
-            regex : "[\\w\\xff-\\u218e\\u2455-\\uffff]+\\b"
+            token: keywordMapper,
+            regex: "[\\w\\xff-\\u218e\\u2455-\\uffff]+\\b"
         }, {
             token: "paren.lparen",
-            regex: /[\[({]/ 
+            regex: /[\[({]/
         }, {
             token: "paren.rparen",
             regex: /[\])}]/
         } ],
+        pipe: [{
+            token: "constant.language",
+            regex: identifierRe + "*",
+            next: "pop"
+        },{
+            token: "error",
+            regex: "",
+            next: "pop"
+        }],
         string: [{
             token: "constant.character.escape",
             regex: escapeRe
@@ -106,6 +132,44 @@ var PrqlHighlightRules = function() {
             token: "error",
             regex: "",
             next: "start"
+        }],
+        fstring: [{
+            token: "constant.character.escape",
+            regex: escapeRe
+        }, {
+            token: "string.end",
+            regex: '"',
+            next: "start"
+        }, {
+            token: "invalid.illegal",
+            regex: bidi
+        }, {
+            token: "paren.lparen",
+            regex: "{",
+            push: "fstringParenRules"
+        }, {
+            token: "invalid.illegal",
+            regex: bidi
+        }, {
+            defaultToken: "string"
+        }],
+        fstringParenRules: [{
+            token: "constant.language",
+            regex: "^" + identifierRe + "*"
+        }, {
+            token: "paren.rparen",
+            regex: "}",
+            next: "pop"
+        }],
+        rstring: [{
+            token: "string.end",
+            regex: '"',
+            next: "start"
+        }, {
+            token: "invalid.illegal",
+            regex: bidi
+        }, {
+            defaultToken: "string"
         }]
     };