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impl FromMeta for syn::ExprPath #170

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merged 2 commits into from
Mar 30, 2022
Merged

impl FromMeta for syn::ExprPath #170

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96c85ba
Create macro for impl FromMeta on syn types which impl Parse
TedDriggs Mar 30, 2022
c1780eb
impl FromMeta for syn::ExprPath
TedDriggs Mar 30, 2022
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102 changes: 29 additions & 73 deletions core/src/from_meta.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -238,25 +238,6 @@ macro_rules! from_meta_float {
from_meta_float!(f32);
from_meta_float!(f64);

/// Parsing support for identifiers. This attempts to preserve span information
/// when available, but also supports parsing strings with the call site as the
/// emitted span.
impl FromMeta for syn::Ident {
fn from_string(value: &str) -> Result<Self> {
syn::parse_str(value).map_err(|_| Error::unknown_value(value))
}

fn from_value(value: &Lit) -> Result<Self> {
if let Lit::Str(ref ident) = *value {
ident
.parse()
.map_err(|_| Error::unknown_lit_str_value(ident))
} else {
Err(Error::unexpected_lit_type(value))
}
}
}

/// Parsing support for punctuated. This attempts to preserve span information
/// when available, but also supports parsing strings with the call site as the
/// emitted span.
Expand All @@ -272,32 +253,32 @@ impl<T: syn::parse::Parse, P: syn::parse::Parse> FromMeta for syn::punctuated::P
}
}

/// Parsing support for an expression, i.e. `example = "1 + 2"`.
impl FromMeta for syn::Expr {
fn from_value(value: &Lit) -> Result<Self> {
if let Lit::Str(ref ident) = *value {
ident
.parse::<syn::Expr>()
.map_err(|_| Error::unknown_lit_str_value(ident))
} else {
Err(Error::unexpected_lit_type(value))
}
}
}
macro_rules! from_syn_parse {
($ty:path) => {
impl FromMeta for $ty {
fn from_string(value: &str) -> Result<Self> {
syn::parse_str(value).map_err(|_| Error::unknown_value(value))
}

/// Parsing support for an array, i.e. `example = "[1 + 2, 2 - 2, 3 * 4]"`.
impl FromMeta for syn::ExprArray {
fn from_value(value: &Lit) -> Result<Self> {
if let Lit::Str(ref ident) = *value {
ident
.parse::<syn::ExprArray>()
.map_err(|_| Error::unknown_lit_str_value(ident))
} else {
Err(Error::unexpected_lit_type(value))
fn from_value(value: &::syn::Lit) -> Result<Self> {
if let ::syn::Lit::Str(ref v) = *value {
v.parse::<$ty>()
.map_err(|_| Error::unknown_lit_str_value(v))
} else {
Err(Error::unexpected_lit_type(value))
}
}
}
}
};
}

from_syn_parse!(syn::Ident);
from_syn_parse!(syn::Expr);
from_syn_parse!(syn::ExprArray);
from_syn_parse!(syn::ExprPath);
from_syn_parse!(syn::Path);
from_syn_parse!(syn::WhereClause);

macro_rules! from_numeric_array {
($ty:ident) => {
/// Parsing an unsigned integer array, i.e. `example = "[1, 2, 3, 4]"`.
Expand Down Expand Up @@ -327,24 +308,6 @@ from_numeric_array!(u32);
from_numeric_array!(u64);
from_numeric_array!(usize);

/// Parsing support for paths. This attempts to preserve span information when available,
/// but also supports parsing strings with the call site as the emitted span.
impl FromMeta for syn::Path {
fn from_string(value: &str) -> Result<Self> {
syn::parse_str(value).map_err(|_| Error::unknown_value(value))
}

fn from_value(value: &Lit) -> Result<Self> {
if let Lit::Str(ref path_str) = *value {
path_str
.parse()
.map_err(|_| Error::unknown_lit_str_value(path_str))
} else {
Err(Error::unexpected_lit_type(value))
}
}
}

impl FromMeta for syn::Lit {
fn from_value(value: &Lit) -> Result<Self> {
Ok(value.clone())
Expand Down Expand Up @@ -380,20 +343,6 @@ impl FromMeta for syn::Meta {
}
}

impl FromMeta for syn::WhereClause {
fn from_string(value: &str) -> Result<Self> {
syn::parse_str(value).map_err(|_| Error::unknown_value(value))
}

fn from_value(value: &Lit) -> Result<Self> {
if let syn::Lit::Str(s) = value {
s.parse().map_err(|_| Error::unknown_lit_str_value(s))
} else {
Err(Error::unexpected_lit_type(value))
}
}
}

impl FromMeta for Vec<syn::WherePredicate> {
fn from_string(value: &str) -> Result<Self> {
syn::WhereClause::from_string(&format!("where {}", value))
Expand Down Expand Up @@ -823,6 +772,13 @@ mod tests {
fm::<syn::Expr>(quote!(ignore = "{ a_statement(); in_a_block }"));
}

#[test]
fn test_expr_path() {
fm::<syn::ExprPath>(quote!(ignore = "std::mem::replace"));
fm::<syn::ExprPath>(quote!(ignore = "x"));
fm::<syn::ExprPath>(quote!(ignore = "example::<Test>"));
}

#[test]
fn test_number_array() {
assert_eq!(
Expand Down