92 lines
1.2 KiB
Plaintext
92 lines
1.2 KiB
Plaintext
// This is the yacc input for creating the parser for interpolation
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// expressions in Go.
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// To build it:
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//
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// go tool yacc -p "expr" expr.y (produces y.go)
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//
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%{
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package config
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import (
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"fmt"
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)
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%}
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%union {
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expr Interpolation
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str string
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variable InterpolatedVariable
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args []Interpolation
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}
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%type <args> args
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%type <expr> expr
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%type <str> string
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%type <variable> variable
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%token <str> STRING IDENTIFIER
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%token <str> COMMA LEFTPAREN RIGHTPAREN
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%%
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top:
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expr
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{
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exprResult = $1
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}
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expr:
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string
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{
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$$ = &LiteralInterpolation{Literal: $1}
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}
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| variable
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{
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$$ = &VariableInterpolation{Variable: $1}
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}
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| IDENTIFIER LEFTPAREN args RIGHTPAREN
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{
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f, ok := Funcs[$1]
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if !ok {
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exprErrors = append(exprErrors, fmt.Errorf(
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"Unknown function: %s", $1))
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}
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$$ = &FunctionInterpolation{Func: f, Args: $3}
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}
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args:
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{
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$$ = nil
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}
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| expr COMMA expr
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{
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$$ = append($$, $1, $3)
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}
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| expr
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{
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$$ = append($$, $1)
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}
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string:
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STRING
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{
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$$ = $1
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}
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variable:
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IDENTIFIER
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{
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var err error
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$$, err = NewInterpolatedVariable($1)
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if err != nil {
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exprErrors = append(exprErrors, fmt.Errorf(
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"Error parsing variable '%s': %s", $1, err))
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}
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}
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%%
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