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lang: parser: Define variable identifier in the parser

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Instead of in the lexer. I think this simplifies things and gives the
parser more information which should hopefully make it easier to parse
without shift/reduce conflicts.
This commit is contained in:
James Shubin
2023-10-11 14:48:22 -04:00
parent 04fd330733
commit 9e7b7fbb3a
2 changed files with 22 additions and 34 deletions
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8
lang/parser/lexer.nex
View File

@@ -295,14 +295,6 @@
panic(fmt.Sprintf("error lexing FLOAT, got: %v", err))
}
}
/\$[a-z]([a-z0-9_]*[a-z0-9]+)?/
{
// an alternate pattern: /\$[a-z](|[a-z0-9_]*[a-z0-9])/
yylex.pos(lval) // our pos
s := yylex.Text()
lval.str = s[1:len(s)] // remove the leading $
return VAR_IDENTIFIER
}
/[a-z]([a-z0-9_]*[a-z0-9]+)?/
{
yylex.pos(lval) // our pos

48
lang/parser/parser.y
View File

@@ -85,7 +85,7 @@ func init() {
%token COMMA COLON SEMICOLON
%token ELVIS ROCKET ARROW DOT
%token BOOL_IDENTIFIER STR_IDENTIFIER INT_IDENTIFIER FLOAT_IDENTIFIER
%token MAP_IDENTIFIER STRUCT_IDENTIFIER VARIANT_IDENTIFIER VAR_IDENTIFIER
%token MAP_IDENTIFIER STRUCT_IDENTIFIER VARIANT_IDENTIFIER
%token RES_IDENTIFIER
%token IDENTIFIER CAPITALIZED_IDENTIFIER
%token FUNC_IDENTIFIER
@@ -112,10 +112,10 @@ func init() {
%error IDENTIFIER STRING OPEN_CURLY IDENTIFIER ROCKET INTEGER CLOSE_CURLY: errstrParseExpectingComma
%error IDENTIFIER STRING OPEN_CURLY IDENTIFIER ROCKET FLOAT CLOSE_CURLY: errstrParseExpectingComma
%error VAR_IDENTIFIER EQ BOOL: errstrParseAdditionalEquals
%error VAR_IDENTIFIER EQ STRING: errstrParseAdditionalEquals
%error VAR_IDENTIFIER EQ INTEGER: errstrParseAdditionalEquals
%error VAR_IDENTIFIER EQ FLOAT: errstrParseAdditionalEquals
%error var_identifier EQ BOOL: errstrParseAdditionalEquals
%error var_identifier EQ STRING: errstrParseAdditionalEquals
%error var_identifier EQ INTEGER: errstrParseAdditionalEquals
%error var_identifier EQ FLOAT: errstrParseAdditionalEquals
%%
top:
@@ -510,7 +510,7 @@ call:
}
// calling a function that's stored in a variable (a lambda)
// `$foo(4, "hey")` # call function value
| VAR_IDENTIFIER OPEN_PAREN call_args CLOSE_PAREN
| dotted_var_identifier OPEN_PAREN call_args CLOSE_PAREN
{
posLast(yylex, yyDollar) // our pos
$$.expr = &ast.ExprCall{
@@ -811,14 +811,14 @@ args:
;
arg:
// `$x`
VAR_IDENTIFIER
var_identifier
{
$$.arg = &interfaces.Arg{
Name: $1.str,
}
}
// `$x <type>`
| VAR_IDENTIFIER type
| var_identifier type
{
$$.arg = &interfaces.Arg{
Name: $1.str,
@@ -828,7 +828,7 @@ arg:
;
bind:
// `$s = "hey"`
VAR_IDENTIFIER EQUALS expr
var_identifier EQUALS expr
{
posLast(yylex, yyDollar) // our pos
$$.stmt = &ast.StmtBind{
@@ -838,7 +838,7 @@ bind:
}
// `$x bool = true`
// `$x int = if true { 42 } else { 13 }`
| VAR_IDENTIFIER type EQUALS expr
| var_identifier type EQUALS expr
{
posLast(yylex, yyDollar) // our pos
var expr interfaces.Expr = $4.expr
@@ -855,7 +855,7 @@ bind:
/* TODO: do we want to include this?
// resource bind
rbind:
VAR_IDENTIFIER EQUALS resource
var_identifier EQUALS resource
{
posLast(yylex, yyDollar) // our pos
// XXX: this kind of bind is different than the others, because
@@ -1261,7 +1261,7 @@ type_func_arg:
}
// `$x <type>`
// XXX: should we allow specifying the arg name here?
| VAR_IDENTIFIER type
| var_identifier type
{
$$.arg = &interfaces.Arg{
Name: $1.str,
@@ -1282,6 +1282,14 @@ undotted_identifier:
$$.str = $1.str
}
;
var_identifier:
// eg: $ foo (dollar prefix + identifier)
DOLLAR undotted_identifier
{
posLast(yylex, yyDollar) // our pos
$$.str = $2.str // don't include the leading $
}
;
dotted_identifier:
undotted_identifier
{
@@ -1296,23 +1304,11 @@ dotted_identifier:
;
// there are different ways the lexer/parser might choose to represent this...
dotted_var_identifier:
// eg: $foo (no dots)
VAR_IDENTIFIER
{
posLast(yylex, yyDollar) // our pos
$$.str = $1.str
}
// eg: $foo . bar.baz (identifier + dotted identifier)
| VAR_IDENTIFIER DOT dotted_identifier
{
posLast(yylex, yyDollar) // our pos
$$.str = $1.str + interfaces.ModuleSep + $3.str
}
// eg: $ foo.bar.baz (dollar prefix + dotted identifier)
| DOLLAR dotted_identifier
DOLLAR dotted_identifier
{
posLast(yylex, yyDollar) // our pos
$$.str = $2.str
$$.str = $2.str // don't include the leading $
}
;
capitalized_res_identifier: