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How to preserve whitespace separators?

See original GitHub issue

Issue type

Bug Report: no
Feature Request: no
Question: yes
Not an issue: no

Prerequisites

Can you reproduce the issue?: yes
Did you search the repository issues?: yes
Did you check the forums?: yes
Did you perform a web search (google, yahoo, etc)?: yes

I am struggling to make PEG.js parser keep original whitespaces of the equation.

Current behavior: 2 * 5 + SUM(1, 2, 3)

[
   "2",
   "*",
   "5",
   "+",
   "SUM",
   "(",
   [
      "1",
      ",",
      "2",
      ",",
      "3"
   ],
   ")"
]

Desired behaviour: 2 * 5 + SUM(1, 2, 3)

[
   "2",
   " ",
   "*",
   " ",
   "5",
   " ",
   "+",
   " ",
   "SUM",
   "(",
   [
      "1",
      ",",
      " ",
      "2",
      ",",
      " ",
      "3"
   ],
   ")"
]

Grammar to copy: https://pastebin.com/zpwqT6Uw PEG.js playground https://pegjs.org/online

What am I missing?

Issue Analytics

State:
Created 4 years ago
Comments:6 (1 by maintainers)

Top GitHub Comments

3reactions

Seb35commented, Apr 2, 2020

@marek-baranowski Another gentle ping 😺

Also, I wrote a PEG.js plugin pegjs-syntactic-actions to facilitate debugging of grammars, and specifically see what characters are captured by what rule independently of the actions, which is probably your issue here as explained by @StoneCypher.

The reasoning of this plugin is: I find it is often/sometimes difficult to understand the global result when it is not what we expect, because it results from the combination of many small actions, and finding the action which behaves badly/stangely could be time-consuming. With this plugin, we see what rule captures what character, and it gives the name of the action to act on.

1reaction

StoneCyphercommented, Apr 2, 2020

oh wow this is really neat actually

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