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Support embedded expressions/braces in double quoted strings #26

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Support embedded expressions/braces in double quoted strings #26

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59f24ba
Support embedded exp/braces in double quoted strings
Nicholas-Lin Aug 5, 2021
0a755db
Fix false comments in strings
Nicholas-Lin Aug 5, 2021
dcac79b
Add test cases for false comments in double quotes
Nicholas-Lin Aug 5, 2021
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45 changes: 39 additions & 6 deletions grammar.js
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Original file line number Diff line number Diff line change
Expand Up @@ -406,14 +406,47 @@ const rules = {

// prettier-ignore
string: $ =>
token(
choice(
/'(\\'|\\\\|\\?[^'\\])*'/,
/"(\\"|\\\\|\\?[^"\\])*"/,
),
choice(
$._single_quoted_string,
$._double_quoted_string,
),

// Breakout single quoted string for symmetry with double quoted strings.
_single_quoted_string: $ => /'(\\'|\\\\|\\?[^'\\])*'/,

// Reference: https://docs.hhvm.com/hack/source-code-fundamentals/literals#string-literals__double-quoted-string-literals
_double_quoted_string: $ =>
seq(
'"',
choice.rep($._string_character, $._escape_sequence, $.embedded_expression, $.embedded_brace_expression),
'"',
),

_string_character: $ => choice(token(/([^"\\])/), token(prec(1, choice('#', '//', '/*')))),
Comment on lines +421 to +425
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From last time we talked, did you try putting repeating $._string_character in it's own rule, so we can just have a $.string_body rule that encompass a full consecutive string?

string_body: $ => rep1($._string_character)

or

string_body: $ => rep1(choice(token(/([^"\\])/), token(prec(1, choice('#', '//', '/*')))))

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Also, this is a nit, but I don't think you need token around /([^"\\])/. And that rule also doesn't have to use a regex group anymore () since there's only one option.

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When I try that it creates a conflict. Any suggestions for resolving it?

Unresolved conflict for symbol sequence:

  '"'  string_body_repeat1  •  '_string_character_token1'  …

Possible interpretations:

  1:  '"'  (string_body  string_body_repeat1)  •  '_string_character_token1'  …
  2:  '"'  (string_body_repeat1  string_body_repeat1  •  string_body_repeat1)

Possible resolutions:

  1:  Specify a left or right associativity in `string_body`
  2:  Add a conflict for these rules: `string_body`

I suspect that adding this rule as is might lead some problems. Tree-sitter prioritizes matching based on length. Say for example we have:

"sometext$var"

I think the $ will be captured as part of the string body instead of an embedded expression, and therefore the whole thing will be parsed as a string body. We might need to make some modifications to accommodate this.

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@aosq aosq Aug 19, 2021 •
edited
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I think you'd want right associativity for $.string_body since that'll capture the largest node. Left associativity would capture the $.string_body on first match so it'd end up just capturing individual characters like it does without the repeat1.

If we run into problems with $ and {, we could do something like we do for $.xhp_comment where we exclude problematic token characters and only allow them in specific sequences. Something like,

  string_body: $ =>
    repeat1(
      choice(
        seq(opt('\\'), choice(/[^"\\${]/, token(prec(1, choice('#', '//', '/*'))))),
        seq(
          // $ is allowed only if not followed by an identifier character
          repeat1('$'),
          opt('\\'),
          choice(/[^"\\${a-zA-Z_\x80-\xff]/, token(prec(1, choice('#', '//', '/*')))),
        ),
        seq(
          // { is allowed only if not followed by $
          repeat1('{'),
          opt('\\'),
          choice(/[^"\\${]/, token(prec(1, choice('#', '//', '/*')))),
        ),
      ),
    ),

I checked out your branch and tried adding right associativity to repeating $. _string_character and it doesn't seem conflict with $.variable (honestly surprised it doesn't cause issues (at least not immediate ones)).


// These are the relevant escape sequences that will affect parsing an embedded expression in the string
_escape_sequence: $ => token(seq('\\', opt(choice('\\', '"', '$', '{',)))),

embedded_expression: $ => seq($._embedded_expression),

_embedded_expression: $ =>
choice(
$.variable,
alias($._embedded_subscript_expression, $.subscript_expression),
alias($._embedded_selection_expression, $.selection_expression),
),

_embedded_subscript_expression: $ =>
seq($.variable, '[', opt($._expression), ']'),

_embedded_selection_expression: $ =>
seq(
$.variable,
field('selection_operator', choice('?->', '->')),
$._variablish,
),

prefixed_string: $ => seq(field('prefix', $.identifier), $.string),
prefixed_string: $ => prec(-1, seq(field('prefix', $.identifier), $.string)),

// Types

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234 changes: 224 additions & 10 deletions src/grammar.json
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Original file line number Diff line number Diff line change
Expand Up @@ -1941,38 +1941,252 @@
]
},
"string": {
"type": "CHOICE",
"members": [
{
"type": "SYMBOL",
"name": "_single_quoted_string"
},
{
"type": "SYMBOL",
"name": "_double_quoted_string"
}
]
},
"_single_quoted_string": {
"type": "PATTERN",
"value": "'(\\\\'|\\\\\\\\|\\\\?[^'\\\\])*'"
},
"_double_quoted_string": {
"type": "SEQ",
"members": [
{
"type": "STRING",
"value": "\""
},
{
"type": "REPEAT",
"content": {
"type": "CHOICE",
"members": [
{
"type": "SYMBOL",
"name": "_string_character"
},
{
"type": "SYMBOL",
"name": "_escape_sequence"
},
{
"type": "SYMBOL",
"name": "embedded_expression"
},
{
"type": "SYMBOL",
"name": "embedded_brace_expression"
}
]
}
},
{
"type": "STRING",
"value": "\""
}
]
},
"_string_character": {
"type": "CHOICE",
"members": [
{
"type": "TOKEN",
"content": {
"type": "PATTERN",
"value": "([^\"\\\\])"
}
},
{
"type": "TOKEN",
"content": {
"type": "PREC",
"value": 1,
"content": {
"type": "CHOICE",
"members": [
{
"type": "STRING",
"value": "#"
},
{
"type": "STRING",
"value": "//"
},
{
"type": "STRING",
"value": "/*"
}
]
}
}
}
]
},
"_escape_sequence": {
"type": "TOKEN",
"content": {
"type": "CHOICE",
"type": "SEQ",
"members": [
{
"type": "PATTERN",
"value": "'(\\\\'|\\\\\\\\|\\\\?[^'\\\\])*'"
"type": "STRING",
"value": "\\"
},
{
"type": "PATTERN",
"value": "\"(\\\\\"|\\\\\\\\|\\\\?[^\"\\\\])*\""
"type": "CHOICE",
"members": [
{
"type": "CHOICE",
"members": [
{
"type": "STRING",
"value": "\\"
},
{
"type": "STRING",
"value": "\""
},
{
"type": "STRING",
"value": "$"
},
{
"type": "STRING",
"value": "{"
}
]
},
{
"type": "BLANK"
}
]
}
]
}
},
"prefixed_string": {
"embedded_expression": {
"type": "SEQ",
"members": [
{
"type": "FIELD",
"name": "prefix",
"type": "SYMBOL",
"name": "_embedded_expression"
}
]
},
"_embedded_expression": {
"type": "CHOICE",
"members": [
{
"type": "SYMBOL",
"name": "variable"
},
{
"type": "ALIAS",
"content": {
"type": "SYMBOL",
"name": "identifier"
"name": "_embedded_subscript_expression"
},
"named": true,
"value": "subscript_expression"
},
{
"type": "ALIAS",
"content": {
"type": "SYMBOL",
"name": "_embedded_selection_expression"
},
"named": true,
"value": "selection_expression"
}
]
},
"_embedded_subscript_expression": {
"type": "SEQ",
"members": [
{
"type": "SYMBOL",
"name": "variable"
},
{
"type": "STRING",
"value": "["
},
{
"type": "CHOICE",
"members": [
{
"type": "SYMBOL",
"name": "_expression"
},
{
"type": "BLANK"
}
]
},
{
"type": "STRING",
"value": "]"
}
]
},
"_embedded_selection_expression": {
"type": "SEQ",
"members": [
{
"type": "SYMBOL",
"name": "variable"
},
{
"type": "FIELD",
"name": "selection_operator",
"content": {
"type": "CHOICE",
"members": [
{
"type": "STRING",
"value": "?->"
},
{
"type": "STRING",
"value": "->"
}
]
}
},
{
"type": "SYMBOL",
"name": "string"
"name": "_variablish"
}
]
},
"prefixed_string": {
"type": "PREC",
"value": -1,
"content": {
"type": "SEQ",
"members": [
{
"type": "FIELD",
"name": "prefix",
"content": {
"type": "SYMBOL",
"name": "identifier"
}
},
{
"type": "SYMBOL",
"name": "string"
}
]
}
},
"_type": {
"type": "CHOICE",
"members": [
Expand Down
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