parser: Refactor finishTopicReference

Reduce duplication in parseV8Intrinsic.
babel · Jun 5, 2021 · b1dd014 · b1dd014
1 parent efdac2d
commit b1dd014
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Showing 2 changed files with 81 additions and 89 deletions.
diff --git a/packages/babel-parser/src/parser/expression.js b/packages/babel-parser/src/parser/expression.js
@@ -1243,9 +1243,30 @@ export default class ExpressionParser extends LValParser {
 
       case tt.modulo:
       case tt.hash: {
-        node = this.maybeParseTopicReference();
-        if (node) {
-          return node;
+        const pipeProposal = this.getPluginOption(
+          "pipelineOperator",
+          "proposal",
+        );
+
+        if (pipeProposal) {
+          // A pipe-operator proposal is active,
+          // although its configuration might not match the current token’s type.
+          node = this.startNode();
+          const start = this.state.start;
+          const tokenType = this.state.type;
+
+          // Consume the current token.
+          this.next();
+
+          // If the pipe-operator plugin’s configuration matches the current token’s type,
+          // then this will return `node`, will have been finished as a topic reference.
+          // Otherwise, this will throw a `PipeTopicUnconfiguredToken` error.
+          return this.finishTopicReference(
+            node,
+            start,
+            pipeProposal,
+            tokenType,
+          );
         }
       }
 
@@ -1268,91 +1289,69 @@ export default class ExpressionParser extends LValParser {
     }
   }
 
-  // This helper method attempts to parse a topic reference
-  // into a new node.
+  // This helper method attempts to finish the given `node`
+  // into a topic-reference node for the given `pipeProposal`.
   // See <https://github.com/js-choi/proposal-hack-pipes>.
   //
+  // This helper method attempts to finish the given `node`
+  // into a topic-reference node for the given `pipeProposal`.
+  // The method assumes that any topic token was consumed before it was called.
+  //
   // If the `pipelineOperator` plugin is active,
   // and if the given `tokenType` matches the plugin’s configuration,
-  // then this method will return a new node.
+  // then this method will return the finished `node`.
   //
   // If the `pipelineOperator` plugin is active,
   // but if the given `tokenType` does not match the plugin’s configuration,
   // then this method will throw a `PipeTopicUnconfiguredToken` error.
-  //
-  // When an appropriate `pipelineOperator` proposal is not active,
-  // this method returns `undefined`.
-  maybeParseTopicReference(): ?N.Expression {
-    // `pipeProposal` is falsy when an input program
-    // contains a topic reference on its own,
-    // outside of a pipe expression,
-    // and without having turned on the pipelineOperator plugin.
-    const pipeProposal = this.getPluginOption("pipelineOperator", "proposal");
-    if (pipeProposal) {
-      // A pipe-operator proposal is active.
-
-      const tokenType = this.state.type;
-
-      if (this.testTopicReferenceConfiguration(pipeProposal, tokenType)) {
-        // The token matches the plugin’s configuration.
-        // The token is therefore a topic reference.
-
-        const node = this.startNode();
-
-        // Consume the token.
-        this.next();
-
-        const start = this.state.start;
-
-        return this.finishTopicReferenceNode(node, start, pipeProposal);
-      } else {
-        // The token does not match the plugin’s configuration.
-        const start = this.state.start;
-        throw this.raise(
-          start,
-          Errors.PipeTopicUnconfiguredToken,
-          tokenType.label,
-        );
-      }
-    }
-  }
-
-  // This helper method attempts to finish the given `node`
-  // into a topic-reference node for the given `pipeProposal`.
-  // The method assumes that any topic token was consumed before it was called.
-  finishTopicReferenceNode(
+  finishTopicReference(
     node: N.Node,
     start: number,
     pipeProposal: string,
-  ): ?N.Expression {
-    // Determine the node type for the topic reference
-    // that is appropriate for the active pipe-operator proposal.
-    let nodeType;
-    if (pipeProposal === "smart") {
-      nodeType = "PipelinePrimaryTopicReference";
-    } else {
-      // The proposal must otherwise be "hack",
-      // as enforced by testTopicReferenceConfiguration.
-      nodeType = "TopicReference";
-    }
+    tokenType: TokenType,
+  ): N.Expression {
+    if (this.testTopicReferenceConfiguration(pipeProposal, start, tokenType)) {
+      // The token matches the plugin’s configuration.
+      // The token is therefore a topic reference.
 
-    if (!this.topicReferenceIsAllowedInCurrentContext()) {
-      // The topic reference is not allowed in the current context:
-      // it is outside of a pipe body.
-      // Raise recoverable errors.
+      const start = this.state.start;
+
+      // Determine the node type for the topic reference
+      // that is appropriate for the active pipe-operator proposal.
+      let nodeType;
       if (pipeProposal === "smart") {
-        this.raise(start, Errors.PrimaryTopicNotAllowed);
+        nodeType = "PipelinePrimaryTopicReference";
       } else {
-        // In this case, `pipeProposal === "hack"` is true.
-        this.raise(start, Errors.PipeTopicUnbound);
+        // The proposal must otherwise be "hack",
+        // as enforced by testTopicReferenceConfiguration.
+        nodeType = "TopicReference";
+      }
+
+      if (!this.topicReferenceIsAllowedInCurrentContext()) {
+        // The topic reference is not allowed in the current context:
+        // it is outside of a pipe body.
+        // Raise recoverable errors.
+        if (pipeProposal === "smart") {
+          this.raise(start, Errors.PrimaryTopicNotAllowed);
+        } else {
+          // In this case, `pipeProposal === "hack"` is true.
+          this.raise(start, Errors.PipeTopicUnbound);
+        }
       }
-    }
 
-    // Register the topic reference so that its pipe body knows
-    // that its topic was used at least once.
-    this.registerTopicReference();
+      // Register the topic reference so that its pipe body knows
+      // that its topic was used at least once.
+      this.registerTopicReference();
 
-    return this.finishNode(node, nodeType);
+      return this.finishNode(node, nodeType);
+    } else {
+      // The token does not match the plugin’s configuration.
+      throw this.raise(
+        start,
+        Errors.PipeTopicUnconfiguredToken,
+        tokenType.label,
+      );
+    }
   }
 
   // This helper method tests whether the given token type
@@ -1366,6 +1365,7 @@ export default class ExpressionParser extends LValParser {
   // then an error is thrown.
   testTopicReferenceConfiguration(
     pipeProposal: string,
+    start: number,
     tokenType: TokenType,
   ): boolean {
     switch (pipeProposal) {
@@ -1379,7 +1379,7 @@ export default class ExpressionParser extends LValParser {
       case "smart":
         return tokenType === tt.hash;
       default:
-        throw this.raise(this.state.start, Errors.PipeTopicRequiresHackPipes);
+        throw this.raise(start, Errors.PipeTopicRequiresHackPipes);
     }
   }
 

diff --git a/packages/babel-parser/src/plugins/v8intrinsic.js b/packages/babel-parser/src/plugins/v8intrinsic.js
@@ -1,7 +1,6 @@
 import type Parser from "../parser";
 import { types as tt } from "../tokenizer/types";
 import * as N from "../types";
-import { Errors } from "../parser/error";
 
 export default (superClass: Class<Parser>): Class<Parser> =>
   class extends superClass {
@@ -28,28 +27,21 @@ export default (superClass: Class<Parser>): Class<Parser> =>
           "pipelineOperator",
           "proposal",
         );
-
         if (pipeProposal) {
-          // A pipe-operator proposal is active.
-          const moduloTopicTokenIsActive = this.testTopicReferenceConfiguration(
+          // A pipe-operator proposal is active,
+          // although its configuration might not match `%` as a topic token.
+          // If the pipe-operator plugin’s configuration matches the current token’s type,
+          // then this will return `node`, will have been finished as a topic reference.
+          // Otherwise, this will throw a `PipeTopicUnconfiguredToken` error.
+          return this.finishTopicReference(
+            node,
+            start,
             pipeProposal,
             tt.modulo,
           );
-
-          if (moduloTopicTokenIsActive) {
-            // The token matches the plugin’s configuration.
-            // The token is therefore a topic reference.
-            return this.finishTopicReferenceNode(node, start, pipeProposal);
-          } else {
-            // The token does not match the plugin’s configuration.
-            throw this.raise(
-              start,
-              Errors.PipeTopicUnconfiguredToken,
-              tt.modulo.label,
-            );
-          }
         } else {
           // A pipe-operator proposal is not active.
+          // Throw a fatal syntax error.
           this.unexpected(start);
         }
       }